Sir, this is a question related to dynamic viscosity. I want to know that physical significance of N that will comes in the dynamic viscosity relations, sir. Yes, okay. So, the question is about dynamic viscosity relation that we talked about in the morning. Specifically, the power N that the strain rate is raised to, that is the question about. Actually, some of the fluids that we deal with which are the non-Newtonian fluids behave such that they have a non-linear relation between the shear stress and the rate of strain within them. So, that is all that we were trying to point out to you that some fluids will behave such that tau will be proportional to the rate of strain raised to some power which will be not equal to 1. So, physical significance is essentially that some fluids are found to behave in that fashion and some fluids are found to behave in the fashion that tau is equal to mu times du dy which is tau is directly proportional to du dy or the rate of strain which are the Newtonian fluids. So, in nature you are or in some technological applications as well, you find that some fluids behave like the Newtonian fluids, some fluid behave in the non-Newtonian fashion that is about it really. I mean that N is simply to signify that it is a non-Newtonian fluid if it is not equal to 1 that is about it. Amrita Colm, you have a question please go ahead. Sir, can we apply this momentum conservation in Caute flow? Yes. So, the question is whether you can employ momentum conservation in Couette flow. The answer is yes, momentum conservation and mass conservations are universal principles and they will be employed in any flow that you are talking about. Couette flow is just a specific example of a flow. In fact, what we are going to do is two days from now when we talk about the exact solutions, Couette flow will be one of the exact solutions that we will completely work out in terms of the velocity profile determination. So, at that time you will realize how we will employ the mass conservation and the momentum conservation for Couette flow. So, the answer is yes and we will do that in a few days of time. But sir, in that case there is no pressure force that is causing a flow to take place. Yes. So, in the case, well I will really request you to wait for a few days, but let me answer it quickly. So, in case of Couette flow when there is no pressure gradient in the axial direction, it is actually the if you remember the Couette flow setting, there are two plates parallel plates. One is stationary and the other one is set in motion. It is actually the plate that is set in motion that transmits its momentum through the action of viscosity to the subsequent fluid layers and that is how you generate and maintain the flow. So, you do not really necessarily need a pressure gradient to maintain a flow in that situation. We will look at this in detail when we solve the Couette flow problem in a couple of days from now. Thank you. PVEPS Vijay Vada, you have a question? Please go ahead. I have two questions, Professor. Yes. Here is the integral analysis. Hello. Yes. Yes, please go ahead. This is regarding the selection of control volume which is very important for the analysis. What I observed here is in the example two and three, the flow of flat plate and the flow of body, you have selected control volume in a different way that in the example two, flow of flat plate, there is no mass flow across the control volume. There is your set to the streamline. And in the third example, you have selected the control volume in such a way that there is a mass flow across the control volume on the top surface. Yes, so the question is about selection of control volumes. In particular, the two examples, example number two and example number three, where in example two, the control volume is chosen in one manner and the example number three, the control volume is chosen in another manner. So, actually the example number two, you can do the same example with a different choice of a control volume altogether. You can actually re-solve example number two in exactly the same manner as the choice of CV is concerned using the kind of control volume that we chose for example number three. So, for example in example two here, the control volume could be essentially having a horizontal top surface as well, in which case there will be a mass flow rate that will cross the top surface and that needs to be properly accounted for. So, in fact, I have chosen the two different control volumes for these two different examples differently on purpose. So, that in one example, I could show it that you could do it in this manner. In other example, I could show that you can do it with some other choice. But your question is exactly right and what I suggest is that if you are up to it, you can try to redo this example number two with a control volume such that the top surface of the control volume is a horizontal line at the level h. But then accordingly you have to take into account the mass flow rate that will be crossing that top surface. The answer will be the same whether you are choosing the control volume in one fashion or the other. This is regarding jet pump example, example five. Yes. Example five. At the inlet section, there is a jet pressure as well as a surrounding fluid pressure. Yes. But the given condition assumption at the section one pressure is taken as uniform. Is it practically possible? No, no, I mean these are simplified examples in the sense that these are supposed to mimic the real life situation to some extent. Obviously, what you are pointing out is correct that we cannot really have a completely uniform pressure in the jet section as well as the surrounding fluid section. But to simplify the problem to a reasonable extent and yet obtain some reasonable numbers as an estimate in this kind of an example, the problem statement says that you assume as simply or for simplicity the pressure to be uniform in section one. That is essentially the idea. Thank you, sir. Okay, thank you. Yes, Perrier, many am I. You have a question, please go ahead. Yes sir, that example three, the integral analysis 14, the slide integral analysis 15. Yes. So, how do we replace actually the small u with the 2 into capital U y divided by h? Yes. So, yes. So, the question is in example number three of the integral analysis, the profile of the actual velocity at the outlet has been found out. And basically if you realize that let me actually switch to the whiteboard for a second because I can draw it there. So, this is the profile that we are basically looking at. So, y equal to 0 is the center line where the actual velocity is 0. And then it linearly increases to capital U by the time the y value comes to h by 2. So, essentially it is a linear profile. So, you assume that u is equal to some constant times y. And then this constant you can evaluate based on the value of u equal to capital U at y equal to h by 2. So, then u is equal to simply c multiplied by h by 2, which implies that the constant is 2 times capital U over h. And therefore, small u, which is the actual velocity as a function of y, then is 2 times capital U over h multiplied by y, which has been then used in the in the expression. Thank you, sir. Yes, V i t well or please go ahead if you have a question. The question is about the outlet velocity profile in example number 3. And the specific question is how realistic the velocity profile is. And the answer is it is not very realistic, it is actually some sort of a devised profile for the purpose of designing a problem such as this, where you can actually then implement the mass balance and the momentum balance in an appropriate manner. Otherwise, it is not really a very realistic profile that you can actually experimentally observe. Okay. K I T Kolhapur, you have a question please go ahead. Sir, one question for our today morning session sir. Sir, as I am a chemical engineer, what is the difference approach wise, difficulty level wise, application wise in safety for mechanical engineering and safety for chemical engineering. And second question in say up to one session on interior analysis slide number 12, you have used mass rate is equal to U over h. But dimension leap check, dimension comes kg per meter per second. Fine, yeah. So, there are two questions. One is if I read you correctly, how is the CFD analysis to be employed for a chemical engineering type problem. So, I am assuming that you are referring to the fluid being non-Newtonian, if you are dealing with a chemical engineering application situation. In principle, there is no difference between how you employ a CFD analysis for a mechanical engineering application versus how you will employ it for a chemical engineering application. All that you need to do is you need to remember when we said that a CFD analysis always begins with an appropriate set of governing equations. So, the governing equations that we are now going to derive in the next couple of days are for Newtonian fluids. However, similar type of governing equations can be derived from first principles of conservation of mass, momentum and energy for fluids that are non-Newtonian as well. So, once the governing equations have been derived in that fashion, you can go ahead and employ one kind of discretization that we will talk about here and carry out the CFD analysis. So, really speaking, there is no difference in principle between how a mechanical engineering analysis goes and how a chemical engineering analysis goes. It always starts with an appropriate set of governing equations and as long as you have the correct governing equation with you, you can always employ the CFD analysis. That should not be any problem. On the second question, what I have talked about in this example number 3 is that the entire analysis is done on a per unit depth basis so that if you for example, right now I am projecting slide number 14 on the board, you will see that the mass flow rate as you correctly point out will be missing one length dimension. However, that one length dimension is essentially that unit length into the plane of the board or the paper that we are talking about. So, if you want you can always multiply by 1 and that 1 will have the dimension of the length so that the mass flow rate will correctly come out as kg per second. So, there is one more question. Yes, please go ahead. Sir, in I will define viscosity tau is equal to tau is proportional to du by dy raise to n. So, how one should experimentally check whether n is 1 or not so that we can carry out experiments? Well, actually the way you can do it is perhaps you can measure the viscosity in a viscometer and see if it is really following a Newtonian law or not. To be honest with you, I have not really dealt with non-Newtonian fluids so that way I cannot perhaps directly answer your question, but in order for you to realize whether a fluid is Newtonian or not, you will necessarily need to find out its rheological behavior meaning that for various different types of or different values of shear stresses, you measure the strain rates and then you plot a curve of the shear stress versus strain rate and find out whether it is coming linear as a Newtonian fluid should or a non-linear in case of a non-Newtonian fluid. That is the only way to figure out whether the fluid is Newtonian or non-Newtonian and then you can proceed from there. Generally, we have in our laboratory to find, we have viscometers. We can find mu like Reynolds viscometer, Sabert and all. But we never, we do not have any such set up to find strain rate and all those things. So, that is what I got this question exactly. Yes, yes. I actually understand your question. I am not really in a position to answer it immediately. Let me think about it and let me get back to you maybe if not today but by tomorrow. Let me note this question down because I do not think we have the answer right now other than generating a rheological curve which is the curve of tau versus du dy. That is the only way you can figure out whether the fluid is behaving in a Newtonian or non-Newtonian fashion. But let me, let me get back to you on that. Thank you. Yeah. Sviya Naiti Sura, you have a question. Please go ahead. My question here is in the integral analysis 14 seat, how mass moves out of the control volume that is m dot out top? Yes. So, that is the. Second question.  Suppose, here's values are given in these problems, then whether we need to include them in any of the equations? Let me answer the second part first. The question is about in these types of problems, the integral problems if shear stress values are given, if we need to include those. Actually, if you see the drag that will come on an object such as this will be due to both the pressure drag as well as a shear drag because of the shear stress. Now, in this particular situation, the pressure is given to be uniform everywhere. So, therefore, there will be no drag due to pressure. So, in fact, if shear stress values are given on the surface of this particular object, your problem is already solved because then from the shear stress values, you can directly calculate the drag that will come on the object. All you need to do is that at every point on the surface, you will need to calculate the shear force and the axial component of that force, you will need to add in order to get the drag on the object. So, that way, if the shear stress values are given on the surface, your problem is actually already solved. You do not have to really do anything. On the first question, the question was about how do we calculate the mass flow rate that is going across the top surface in this particular example. So, I have already projected the slide on the board. So, if you see here, this is a symmetric problem as we saw. So, let me go back. This is symmetric problem about the central horizontal line and therefore, we have chosen only the top half. We could have chosen the bottom half as well. The bottom surface of this control volume is such that because the problem is symmetric, there is no mass exchange happening across the bottom surface. I hope that is clear. Now, having done that or having said that, if you look at the mass flow rate that is entering this control volume from the left hand side, from a geometric interpretation point of view, if you want to get an idea of the mass flow rate, it is basically the shaded area of the control, of the rectangle that I am highlighting. It is the rectangle which has a length or one dimension of capital U and the other dimension of h by 2. The area under this is what the mass flow rate that is coming into the control volume. That is the geometric way of looking at it. If you look at the outlet, what you see is that, if you calculate then the area of this triangle which has a base of h by 2, let us say, and a height of U, you will see that the area of this triangle is less than the area of the rectangle at the beginning which will represent the mass flow rate coming in. Therefore, there is a mass deficit. There is more mass coming in than what is going out. So, the difference between those two has to be going out from the top surface. There is no other way it can go anywhere is the point that we would like to make here. I hope it is understood. Sir, but whether it is moving out perpendicularly to the control volume or it is coming out at particular direction, that is the more specific question. It is immaterial. It is immaterial to know whether it is moving perpendicular or otherwise. In general, it need not move perpendicular to the control volume surface. In general, you can assume that it is going at some sort of an inclined manner as I have shown here, but that is really immaterial as far as the problem solution is concerned. All you need to realize is that there is a certain non-zero mass flow rate that is leaking past this top surface of the control volume. That is the most essential thing to understand here. Whether it is going in a perpendicular manner or not is really not an important thing. In fact, if it is going in a perpendicular manner, then it actually will mean that in the X momentum, you need not account for it. If it is going in a inclined manner, so to say, it will have a velocity component in the X direction which will cause an X momentum going out from the top surface as what we have done in the problem. Thank you, sir. Okay, thank you. Ruba Indore, you have a question. Please go ahead. Sir, how will establish momentum conservation in fluids which are exceptionally high at viscosity? The question is how will we ensure momentum conservation in fluids which have very high viscosity? And actually the answer is that you do not have to worry about whatever value of the viscosity, whether it is less or more. The basic momentum principle, whether it is on integral basis or later, whether it is on differential basis as we will see in a couple of days, it will always employ or apply. So the viscosity, whether it is low or high, it simply does not matter. It will automatically be taken care of. Sir, because one experiment I read was pitch drop experiment. In that one fluid regarding tar was, one derivative of tar was used and it was, I think it travels inches in years. So I was a bit curious about it. Yes, so it is a very special kind of a fluid and looks like from the description that you have given, it appears to be a non-linear fluid, meaning that it is a non-Newtonian fluid as well. Even if that is the case, the fundamental principles of mass conservation and momentum conservation or momentum equation as we said, they are not going to change whether the fluid is highly viscous or otherwise. So they can still employ or apply without any problem. I do not see any trouble with that. It is just that the time scales over which the flow is happening is very, very large as you say, but that does not violate the principles of mass conservation and momentum equations. Sir, thank you. Okay, thank you. P.C.O.E. Baramati, please go ahead if you have a question. My question is, sir, can change in inlet and outlet portion of control volume affects to all the three mass, energy and momentum balance. Okay, I think I understood your question. So the question is, if the control volume is chosen differently especially with respect to the position of the inlet and outlets, if the balance statements will change. See, as long as the velocity profiles that you are dealing with are not going to be different at the inlet and outlet, the position at which you take the inlet as well as outlet is not really going to change the analysis. Only thing that will change is if the extent, the lateral extent which will permit lesser or larger mass and momentum flow rates coming in, then obviously things will change, but then automatically the balances will make sure that your final answer is correct. So in that sense, there is nothing to worry about. Okay, sir, thank you. Thank you. Yeah, Mufakum Ja, please go ahead if you have a question. To integrate analysis, 14 PPT, 14, in that mass conservation equation has been written, that is correct. That is in that box equation is given. Okay, and when we come to 15, block number 15, there this velocity u is given for the mass that is going out, but that is not correct because the mass is going across the area, across the top area. So we should take that cross-sectional area, not this cross-sectional area so that velocity will be different. Okay, so the question is about whether the expression which I am highlighting right now is correctly worked out or not, especially the value of the velocity chosen is correct or not. So let me just go back to the control volume. So if you look at this slide number 14 which is projected right now, you mentioned that the mass flow rate is correctly calculated, which is good. Now the mass flow rate is actually carried out by a component of the velocity which is perpendicular to the flow, to the surface, control surface. Okay, however in this particular case what we are doing is we are employing the x direction momentum equation. So in the x direction momentum equation what we are interested to know is that the x momentum on a rate basis flowing out and in from the control volume. So if you look at the mass flow rate that is flowing from the top surface of the control volume here, as far as the x momentum that it carries, it has to be multiplied by the velocity in the x direction which exists at this location which is at y equal to h by 2 and if you see the velocity plots that have been shown at the inlet and outlet, you will see that at y equal to h by 2 the x direction velocity is equal to indeed capital U. Therefore the x momentum that the mass flow rate is carrying out of the control volume is equal to the mass flow rate from the top multiplied by the capital U velocity. That is the only thing that needs to be understood here that at y equal to h by 2 which is the top surface of the control volume, the x velocity is actually equal to capital U and therefore the mass flow rate will carry an x momentum which will be the mass flow rate multiplied by that capital U and that is the reason it has been calculated in this fashion. Okay, thank you and the other one is instead of integral analysis, whether differential analysis also could be used for safety? So the question is whether differential analysis could be used in place of integral analysis. See in a problem like this, when the overall objective was to find out the drag, in a situation that is shown on the board right now where you have an inlet velocity profile given, an exit velocity profile given at certain upstream and downstream locations etc. Without resorting to the differential analysis, you are in a position to calculate the drag directly with an integral analysis like this. Now obviously the differential analysis is a detailed analysis, much more detailed analysis. So there what will actually be happening is that you will find out the entire velocity field as it will exist within the domain defined by the control volume in a point wise fashion. So that will be far more information that you will have available with you. Using that information, you can always find out the drag force on this object. So that way differential analysis will always give what you want. It is just that the amount of work required for differential analysis will be enormous whereas in this particular case, using this simple integral analysis, you are able to find out the drag force on this object without really using the differential analysis at all. So that is the advantage of such problems in integral analysis. But the point is that differential analysis will always give what you want. Amritha, Bengaluru, please go ahead if you have a question. Sir, I have two questions. So one is connected to Taylor series of expansion. Is there any mathematical and physical constraints to consider Taylor series? Why? Because most of the cases we consider Taylor series of expansion. Okay, let me try to answer this right away. The Taylor series expansion is used for situations where functions are smooth and nicely behaving as they say when there are no discontinuities and issues such as that. What happens in case of fluid mechanic situations is that as long as you are dealing with a continuum situation in an incompressible situation in particular, what you have is a nice smooth distribution of properties from one point in the domain to the next. So that there is no restriction on the use of Taylor series expansion as far as these types of problems are concerned. So that way there is absolutely no restriction. The second question is we come across conservation form and non-conservation form. In principally though equations looks like simple through mathematical manipulations, but in physically what different meanings it sort about? Yeah, so the question is about conservation form and non-conservation form of governing equations. We are actually going to derive these in the next two days, the governing differential equations both in conservation form as well as in non-conservation form. So hopefully the question will be answered in due course of time, but let me say that at this point what you should perhaps realize that if you employ the inherent Eulerian approach of balancing mass flow rates and momentum flow rates etc. for a control volume, you will automatically get the governing equations in conservative form whereas if you employ the Lagrangian form of derivations, you will always get the equations in non-conservative form. So that way what we will do is we will do actually both and in principle there is no difference between both. In some CFD situations especially when you are using a finite volume technique, it seems that the conservation form of the equations is more useful to be utilized than the non-conservation form. So when it comes to implementation detail using a technique such as finite volume technique, the conservation form works perfectly well, non-conservation form has a problem. However, non-conservation form people have used with finite differencing and that also is an option if you want to pursue. But in a couple of days, we will derive these equations in both forms so that hopefully this question will be clear. Thank you, over and out. Okay, thank you. Yes, Manipal please go ahead if you have a question. And the streamline is diverging from the flat plate at section 2. So naturally when uniform pressure is considered in the x momentum equation for reaction due to the plate that p into a in minus a out should be out should have been considered. But there has been neglected that due to the pressure two terms will be coming p2a2 minus p2a p1a1. Actually p is same and a1 minus a2 should have appeared. Why the areas have been neglected? The streamline is diverging from the flat plate. Inlet flow area is different, outlet flow area is different. Yes, the question is about example number 2 in the integral analysis. The question is whether the pressure forces have been neglected correctly or incorrectly because what is getting pointed out is that the streamline is getting wider so to say from the inlet to the outlet. Therefore the outlet area is larger than the inlet area and therefore the pressure forces should have been considered as higher or the pressure difference between the inlet and outlet is the point. So the answer to that is that the pressure is actually uniform everywhere. It is given as part of the problem and furthermore the control volume is a closed control volume completely. So what ends up happening in a situation such as this where you are dealing with a closed control volume with a uniform pressure everywhere that the pressure contribution cancels out completely when it is acting on a completely closed control volume from all sides. So the one example that you can think about is rather than a continuously widening area of cross section, if you want you can think about a step change in the area that may help you. Let me in fact try to draw it on a whiteboard and try to explain what I am talking about. So let us say that if we were dealing with a closed control volume in this form where you have a step change in the cross section rather than a continuous change and what is given is that the pressure is completely uniform surrounding this control volume. In this particular case you will appreciate the fact that there is no net force due to the pressure on to this control volume. The situation as I have drawn on this whiteboard is no different than what was shown earlier. You can say that the continuously increasing or decreasing cross sectional area is the most general case of a closed control volume whereas what I have drawn here is a special case where you are seeing a step change. See what happens in case of a continuously increasing or decreasing area as what we had in the example is that you need to only look at the projected areas and then the projected areas will make sure that the uniform pressure contribution will cancel completely and there will be no net pressure force because of that on the control volume. VNIT Nagpur if you have a question please go ahead. I have two questions one is related to the morning session on dynamic viscosity. Why does the dynamic viscosity does not change along x direction in this flow and does it remain same for any type of flow? And another second question is on integral analysis 9 P1 is taken as plus while P2 is taken as negative why it is soon? Let me let me try to answer your second question first the integral analysis. The question was on integral analysis slide number 9 P1 was taken as positive whereas P2 was taken as negative and what was the reason for that? See we talked about pressure being a compressive force so as far as the control volume is concerned and the material that is enclosed within the control volume is concerned. Pressure 1 if it has to act in a compressive manner it has to act on the control volume in the positive x direction. So when it comes to calculating the or adding the forces in the x direction it will be basically acting in the plus x direction whereas the force due to pressure at section number 2 here at the outlet will be such that if it has to act as a compressive force it has to act on the control volume in the negative x direction. So when it comes to summing the forces on the control volume in the x direction it will come as a negative force that is acting in the negative x direction. So that is the reason P1 a1 was taken as acting in the x direction whereas P2 a2 was taken as acting in the minus x direction. I hope that answers that yes please go ahead. Why does the dynamic viscosity does not change along x direction in this case? Yeah I am not understanding your question that the dynamic viscosity is not changing in the x direction etc. So can you please point out to which slide or which part you are referring to? Introduction 5 PPT number introduction 5 in that one dynamic viscosity as per the figure the value of dynamic viscosity along x direction is given as mu while along y direction it is given as mu plus dou u by dou y into delta y. Okay now let me try to explain this figure again. So what we are doing here is that this u here is sorry yeah the u here which the highlighter is now pointing out is the axial velocity in the x direction and u plus du dy times delta y is the axial velocity at the point Q. So these are the axial or the x direction velocities and these have nothing to do with the dynamic viscosity. Using these velocities what we are finding out is first we are finding out the shear strain experienced by this vertical segment PQ and then dividing that shear strain by the time interval over which this happens we are finding the rate of shear strain which then turns out to be this du dy. So up to here there is no mention of dynamic viscosity at all here all that we are doing is we are calculating the rate of shear strain in this particular simplified situation of a 1D shear flow. Now if you are asking me why u is only a function of y and u is not a function of x. I will answer this in the fashion that this is what we will call a fully developed situation and in a couple of days of time we will actually talk about the nature of fully developed flows little bit in more detail. At this point you just assume that in a fully developed situation the axial velocity is independent of the axial direction or axial distance. It can be only a function of the lateral distance and that is why u has been chosen to be a function of only y coordinate but u is not a function of x coordinate. I wonder if that answers your question. Sir what is the utility of devising the term kinematic viscosity when as we have defined here dynamic viscosity and understood the significance we have understood the physical significance of dynamic viscosity. As viscosity is broken into dynamic and kinematics so what is the significance of the or why we have devised the term kinematic viscosity and where it is used and like what is the utility of it. Yes, so the question is about the use of term called kinematic viscosity and what is the significance of kinematic viscosity. The kinematic viscosity is defined as the dynamic viscosity divided by the density of the fluid. So, it is mu divided by rho and in principle physically speaking there is no difference in terms of what dynamic viscosity does and what kinematic viscosity does. Both of them are related to momentum transfer within a fluid. So, in some cases what happens in especially in incompressible flows or constant density flows you will see that the governing equations are such that you can divide the governing equations completely through the density and then you end up generating this kinematic viscosity in one of the terms. We will see that in a few days time. However when it comes to the physical interpretation both of them more or less say the same thing namely they tell how momentum is transferred within a fluid and that way there is no difference between those two. Okay, thank you sir. Thank you. Nitte Meenakshi please go ahead if you have a question. Whereas in the example number four why haven't we considered the frictional losses through pipes because in order to conserve we need to consider all the losses also. So, as we come across frictional losses through the pipes flow through pipes why haven't we considered the frictional losses here? So, the question is about whether frictional losses have been considered or not considered in one of the examples. Can you please repeat which example it is? Example number four. Yes, so the see in this case the frictional losses have not been mentioned at all because we are dealing only with mass and momentum conservation. We have not talked about the energy equation at all so far. So, here it was only to deal with what sort of forces the fluid is exerting on the pipe and vice versa. When it comes to the frictional losses as you are mentioning we will we can utilize the energy equation and in the energy equation we incorporate the frictional loss terms. In any case the frictional loss terms is actually inbuilt in the numbers that have been shown in this example in the sense that the frictional loss will cause a pressure loss okay from the inlet to the outlet. So, the pressures that have been given in this case are 400 kPa at the inlet and 300 kPa at the outlet. So, in that sense you can say that the frictional losses through the pipe have already been incorporated by mentioning a pressure loss over the length that has been shown. Uniform pressure there won't be any frictional losses or we neglect the time frictional losses if they are given uniform pressure across the pipe. Uniform pressure. Otherwise it will be rated as an ideal flow wherein there will be no frictional losses. No, no, no this is not an ideal flow. This is indeed a real flow. Only thing is that the mention of frictional losses is not explicitly done here. What has been done is that the problem design is such that there is a pressure drop from the inlet to the outlet as you can see from here 400 kPa to 300 kPa and this pressure loss is supposed to be occurring because of the action of viscosity which will result in frictional losses. So, even though we have not specifically mentioned the frictional losses here because there is a delta P pressure loss from the inlet to the outlet those are supposed to be acting anyway. So, they are built into the problem is what I am trying to say. Kolhapur. Yeah, can I say Kolhapur go ahead please if you have a question. Sir, liquid and gases. What if the solid comes into the picture? Will it, will all the equations follow the same or remains same or there will be any changes? Okay. So, the question is about multi-component flow in some sense where you have solid particles also embedded within the flow and the question is whether anything will change in terms of the equations or not. So, the answer is that yes actually you need to modify the governing equations because there will be terms which will have to be taken into account which take into action or which take into consideration the momentum exchange between the fluid and the solid particles that are suspended in the fluid. So, those have to be incorporated in the governing equations itself. So, that the models that you start with as far as the description of the problem is concerned are going to be different than what we are considering here.  We are not really talking about multi-component situations, but the answer is yes there will be changes and the changes are first reflected in the governing equations themselves. The governing equations have to be modified to take into account the momentum exchange and perhaps the energy exchange that occurs between the solid phase and the liquid phase or the fluid phase. DK, T, A, C, S, L, Karanjee please go on. In plastic injection flow analysis, in plastic injection molding process? The question is how CFD is useful in plastic injection molding process? Unfortunately, I am not at all familiar with the manufacturing processes such as what you mentioned and in principle it appears that there will be some sort of a fluid flow involved and therefore, the kinds of equations that we are dealing with should be applicable assuming that the liquid or the fluid that is involved in there follows the Newtonian law reasonably accurately. If the Newtonian law is not obeyed by the fluid, then the entire set of governing equations has to be rewritten for the kind of fluid that we are dealing with in that particular situation. Once you have the correct set of governing equations, then the methods of CFD can work on those governing equations as well without any change. So, that is the best answer that I can provide right now because I am really not aware of any details in a manufacturing process such as that. Sorry about that. It is moving ahead in the mold then its temperature is goes on decreasing. So, its viscosity goes on increasing. So, its viscosity is not constant. So, how we can apply that equation? Yes. So, the question is actually related to temperature dependent viscosity in a fluid and that is not necessarily a problem at all. In general, if you know how the viscosity of the fluid behaves with temperature, somehow if you have characterized that separately or if the data is available in some other literature, you can incorporate that temperature dependence on viscosity in your CFD analysis and you can perform the CFD analysis. So, having a temperature dependent viscosity is not necessarily a problem at all because that is routinely taken care of by the CFD people. Gajanan Maharaj, College of Engineering, please go ahead if you have a question. Publication flow like gas and liquid, which approach we should use for solving it, either Eulerian or Lagrelyan? The question is about a multi-component flow again when we are dealing with a gas flow with solid particles embedded in it and the question is whether we can employ Eulerian or Lagrangian approach to it. So, actually the question is out of the scope as far as this course is concerned, but let me answer it in the best manner that I can. When it comes to such flows, when you have gas flow and then solid particles embedded in it, there is typically an approach called a Lagrangian-Eulerian combined approach where the fluid flow is solved using the Eulerian approach and the solid particles are tracked with the Lagrangian approach. So, it is what is called as a many times it is what is called as an ALE which is the arbitrary Lagrangian Eulerian approach which is the most common approach used for solving such problems and to the best of my knowledge some of the commercial codes do have this kind of a feature available. However, for our course it is completely out of scope and we will deal with only a single phase fluid flow in this case. I hope that answers your question to some extent. I have one question sir, 13, 13 in that case we have gone through the drag force. Suppose we have to go for the lift force, then how the equations will be different for that case. So, the question is about example number 3 in integral analysis and the question is that we have calculated drag force in this situation. If a lift force was to be obtained, how we can proceed with that? So, it turns out that if you look at this particular example, because it is symmetric about a horizontal central line, the lift in this case is exactly equal to 0. So, in this particular case there will not be any lift force on the object. If it was asymmetric in terms of the flow about the central line, then we will have to think about a lift type force and in which case what we have to do is we have to employ a y direction momentum equation. So, the y direction momentum equation appropriately incorporated should give you a lift force, but in this particular case, because the problem is symmetric about the horizontal line here, horizontal center line, there will be no lift force whatsoever. So, the lift here will be 0. Yes, Amruta School of Engineering column, please go ahead. First of all thank you very much for kindly delivering us very good lecture on food mechanics. I have a question. Of course it is not connected to none of the examples here worked out today. That is, suppose if we take a flow over a cylinder, a circular cylinder, a flow is taking place, of course we know there will be some separation, there will be some shedding of vortices in the downstream. So, applying to this situation, how will you consider the conservative equations? That is, on the upstream side there is only plain flow that is potential flow. Downstream, the flow takes place in three modes, one as vortices, one as a liquid, third one as potential flow. So, there are three modes of mass flows. So, when you consider the conservation equations, how will you treat the conservative equations? Would you please? Yes. So, the question is about flow across a cylinder and what is getting pointed out here is that it is a fairly complex situation in the sense that upstream of the cylinder it will be a plain flow approaching the cylinder, whereas due to the separation over the surface of the cylinder, there will be a vortex shedding at the back of it and then there will be a wake flow and then away from the wake flow there will be again a potential flow sort of a situation. So, how to handle a situation such as this? So, clearly if you want to analyze a problem like this, you have to resort to a CFD analysis which will involve the complete Navier-Stokes equations and if you solve the complete Navier-Stokes equations for a problem like that, all these flow domains that you are referring to will automatically get captured in the appropriate places. In fact, Professor Sharma who is going to deliver the second half of this workshop is actually, he has actually done several such computations for bluff bodies including flow across cylinders. So, perhaps in due course of time what he will show is some of the results from the CFD simulations that he is doing, but in particular what he does is that it is the complete Navier-Stokes system that needs to be solved subject to the appropriate boundary conditions and automatically all these flow features that you are referring to will get captured through a detailed flow simulation. Thank you very much. Yes, VIT Valor please go ahead. Can I go to the example 4? Sir, this axial force, where is acting on the control volume? Yes, the question is where is the axial force acting on the control volume? See, the way this control volume is chosen, we are actually choosing it such that it is cutting across the pipe over the length of interest. So, in principle what is happening is that because of this cutting of the pipe, there will be a reaction from the pipe onto the control volume and that is what is getting calculated as we have worked out the solution in this case. So, if you see the last part on this slide, the reaction which is getting calculated in this particular fashion is the x direction reaction on the control volume due to its interaction with the pipe because the way it has been chosen it is cutting the pipe and the idea is that using the Newton's third law of motion, this force will be exactly equal to the negative of the axial force that the pipe is experiencing because of the fluid that is flowing through it. See, one other way of solving this problem is you choose this control volume such that the top and the bottom surface of the control volume are essentially coinciding with the pipe walls, but they are just inside the pipe walls. In which case what you can argue is that the force that is coming onto the control volume is essentially the frictional force or the reaction of the frictional force let us say onto the control volume and then the negative of that will be the axial force on the pipe. That is one other way of doing it as well. I hope that answers your question. Yes, Nirmah, please go ahead. Sir, I want to know that through porous media, will the flow will be always non-uniform or to you sir? So, the question is about flow through porous medium and if the flow will be always non-uniform, I am not really in a position to answer that because I have never done flow through a porous medium kind of a simulation. However, it appears to me that in general there should be non-uniformity involved if you are dealing with flow through a porous medium. Unfortunately, flow through transport through porous media falls completely out of the scope of this course. So, I may not be able to answer it completely at all, but I think based on what generally I know about this there will be non-uniformity involved in the flow, if it is through a porous medium. That is why I was in doubt that it is a steady non-uniform flow or it will be steady uniform flow. Yes, so the question is coming because the example number 4 dealt with a porous wall pipe. See actually this is a very special situation in the sense that the flow that we are talking about really is happening inside the pipe and it is a completely homogeneous situation, there is no porous medium there. So, the only porous medium that the flow is seeing is the pipe walls and it is not really coming into the analysis as such. What I was trying to answer is if the entire domain within the pipe let us say in this case was a porous medium and then if you were talking about flow through that then whether we will have a non-uniformity or not. But in this particular case the pipe really is completely open and there is no porous medium inside the pipe, the only porous medium is on the walls and that is really not affecting the uniformity of the flow within the pipe. But sir if it is instead of constant cross section, if it is varying cross section then it will affect. Yes, see typically even in this case to assume that the flow is uniform is a fairly big assumption. In general when you are dealing with flows in pipes whether they are porous walled or not, you will not really get a uniform flow type of situation. However for the purpose of simplicity in an example such as this we assume that the flow is uniform across the cross section. In general it will not be the case at all whether the pipe is porous walled or not. Sir what is the main point wise most distribution of the property? Yes, so the question is what is meant by point wise smooth distribution of property. So this refers to our continuum discussion right at the beginning when we said that we will assume that our fluid medium is a continuum medium so that the fluid matter is continuously distributed in the domain of interest. So here if you look at two points within the fluid domain which are very close to each other and if you want to monitor the property such as say density or pressure at these two points which are very close to each other, you will see that you will typically not get a huge jump between the pressure value or the density value from one point to the neighboring point and to the neighboring point and so on. So if you want to represent a pressure as a variable or density as a variable through a mathematical function that mathematical function of pressure as a function of x y z will be a smoothly varying function within the domain. So the value of p or rho or a temperature will vary smoothly from one point to the neighboring point and not drastically is what I was trying to point out. So what is getting pointed out immediately is that the continuum assumption cannot be utilized across a normal shock which is a phenomenon that occurs in a compressible flow type situation where all properties such as density, pressure etc. will change by very very large amount in a very short distance and that is absolutely correct. So within the shock region you cannot employ a continuum assumption and you have to resort to a molecular simulation if you want to actually capture the structure of a shock. In example number three it is written that pressure at those two stations 1 and 2 same so then my question is does flow is possible if the pressure between the two stations remains the same. Yes, so the question is related to example number 3 where in the problem statement it was given that pressure set sections 1 and 2 are the same. The question is whether this is a reasonable realistic assumption or not and the answer is actually it is not. It is absolutely incorrect to assume that the pressure at section 1 and section 2 are going to be more or less the same. In fact, typically you will see that the pressure at section 1 will be higher than how it is at section 2. However, for the purpose of simplicity in an example such as this where the objective was just to sort of show how to implement the integral mass and momentum balances to simplify the situation it has been given that just go ahead and assume that the pressure is the same at section 1 and section 2 that is about it. Thank you. Yes, PVPS Vijay Vada please go ahead. Question where I want to see the role of CFP the application is I want to find out the time to calculate time to for a cooling of a hot coffee in which I am using a sugar and stirring it with a spoon. So, what are the different mechanisms involved with that is it apart from heat transfer mass transfer does CFP has a role in that that is my question. Yes, so the question is pertaining to a specific situation of cooling of a coffee mass contained in a cup when someone is stirring it whether a CFD type simulation can be done of that and the answer is yes it is actually even though we do it on a regular basis day in and day out the fluid mechanics of stirring a coffee contained in a cup is actually very very complex. The reason is one of the things that you may have to consider here is that the flow may be highly turbulent in addition to some other things that are happening. So, for example, as you mentioned if there is some sugar particles in the coffee cup there is perhaps a mass transfer happening as the sugar is getting dissolved in the coffee. So, how much of that affects the flow is another question whether the dissolving of the sugar is actually affecting the flow significantly or not and if it is not perhaps we do not have to bother about this. So, these are what we will call modeling inputs into first deciding what sort of a set of governing equations that we will need to have in order for a problem such as this to be simulated and then because it is a fairly complex problem as far as the present course is concerned we cannot really talk about it much at all, but in principle a CFD simulation can be done to figure out how the coffee will then cool down as you keep stirring about it. The fact is that most likely you will have to resort to a commercial solver to try and do this kind of simulation because the commercial solvers will be fairly sophisticated to try and do this kind of simulation, but that is all that I can say at this point really. Yes, NIT Varangal please go ahead. Sir, one R and D related and small doubts are ahead. So, from the morning itself we are discussing about generally about the convincing systems in CFD generally. Can you apply this CFD analysis to non-conventional energy sources just like solar energy applications or thermal systems, solar heaters like solar cookers like this. Is this concept useful in this area sir? Yes, so the question is about whether we can employ a CFD analysis for the design and let us say analysis of non-conventional energy related equipment such as solar heaters or something of that sort and the answer is yes absolutely there is no question about that. In fact, if you refer to recent literature in many of these energy related journals you will see that people are routinely utilizing CFD analysis for flow inside let us say a parabolic crop collector or any other types of situation including radiation heat transfer. So, people have employed all these kinds of CFD applications for the analysis of non-conventional energy sources as well. So, there is no problem in that. Next question from Michael. Yes, if possible how to model the governing equation considering the flow conditions and the material properties whenever flows are going to be considered in pipes? Yeah, can you please repeat the last part of your question? Yeah, so for example if you are going to be considered the fourth example in the fourth example I would like to generate the governing equation for the consideration of flow conditions as well as flow conditions as well as material properties. If possible can you suggest how I am going to be considered the governing equation? I am sorry I am still unable to understand the last part of the question. So, you are referring to flow through a pipe such as what is shown in example number 4, but then the specific question you are asking is how to incorporate something which I am not getting I am sorry can you please once repeat that again? Next to that fluid structure interaction governing equation for the fourth example. So, the question is about fluid structure interaction type problem whether we can use CFD for fluid structure interaction type problem what sort of governing equations to use is that correct? Yes, so people are using CFD for fluid structure interaction type problems. So, one example I can give you where what we are doing is if there is a thickness to the pipe wall here and there is a high pressure liquid that is flowing through the pipe what we do is we solve the fluid flow problem and we obtain the pressure distribution that is going to be existing on the pipe wall from the inside and then use that pressure distribution as a boundary condition and then solve the structural analysis problem within the pipe wall using the corresponding governing equations from solid mechanics. So, that is one way of doing it which is what we will call a decoupled way meaning that we are first solving the fluid flow problem completely without regard to the solids problem and then utilizing the results from the fluids problem as a boundary condition to solve the governing equations for the solid problem. So, this is one standard way of doing fluid structure interaction problems where you are essentially decoupling the fluid problem from the solid problem and using only the boundary conditions that are generated as a result of the fluid solution for the solid problem, but yes these kinds of applications people are solving with CFD type applications. So, with this we have come to the end of today the first day. Thank you and we will see you tomorrow.


Daily Tech News show is made possible by its listeners, thanks to all of you, including Ken Hayes, Philip Shane, and Paul Boyer. Coming up on DTNS, what's actually going on with the social media moderation law in Texas? Microsoft's plans to let you use game discs on consoles that don't have optical drives and Meta's plan to mix reality for the workplace. This is the Daily Tech News for Thursday, May 12th, 2022 in Los Angeles. I'm Tom Merritt. And from Studio Redwood, I'm Sarah Lane. I'm Austin Texan. I'm Justin Robert Young. I'm the show's producer, Roger Chang. Oh, it's so good that you're from Texas and originally from Florida today, Justin. Oh yeah. No, they don't do troublemaker states. Always. What did it all mean? All right. They're in the spotlight today. Let's start with a few tech things you should know. Twitter CEO, Parag Agrawal, sent a memo to employees announcing that the head of product, Kevon Bacore, is leaving the company and Jay Sullivan will take over the chief of product job that Bacore had for the last several years. Twitter is also freezing most hiring and cutting spending. On Twitter, Bacore interrupted his paternity leave to say this wasn't my decision. Parag asked me to leave after letting me know that he wants to take the team in a different direction. The oversight board, sometimes called the Facebook oversight board, but the actual name is just the oversight board rules both on appeals over moderation decisions as well as policy questions so far entirely related to Metta's Facebook. Facebook is bound to respect the moderation rulings, but only has to consider the advice in the policy rulings. That said, the board has made 18 policy recommendations and Metta has implemented 14 of them. Recently, Metta asked the board to advise on its policies regarding the war in Ukraine. You may recall that Facebook has made an exception to its prohibition against calls for violence if the posts are about Russian soldiers operating in Ukraine. There were also questions about when it should be allowed to show dead bodies or videos of prisoners of war criticizing the conflict, whether it should adapt its rules to this particular situation. However, late last month, Metta withdrew the request to review those policies. The Verges Casey Newton talked to the members of Metta and the board and found that the withdrawal was done over concerns that whatever decision the board might make, Russia might use it as an excuse to retaliate against employees and relatives in Russia. But Newton points out that's something that Russia has already done in response to previous Facebook decisions. NVIDIA is publishing their Linux GPU kernel modules as open source. NVIDIA has offered Linux drivers for years, but they were always proprietary. So NVIDIA's user space software remains closed. Well, but it's mostly good news. That's good. Swedish-backed scientists have published a paper in the journal Scientific Reports showing their findings on the effective video games on 5,000 children aged 10 to 12. The children were asked to report how often they played video games. On average, they reported an hour a day. The scientists then tested the children on reading comprehension, attention and memory, visual spatial processing and learning ability. They controlled for socioeconomic and genetic factors and found that over the space of two years, children in the top 17% of hours playing games, the children who played more than an hour of video games a day, showed an increase in their IQ of 2.5 points over the average. Sonos officially launched its budget soundbar, the Sonos Ray, starting at $279. So, you know, it's budget, depending on who you are, it's budget for Sonos, I suppose. It supports AirPlay 2 and most major music streaming services. It also features touch controls on the top to raise that can be used with a Sonos One for surround sound. No built-in mic though, no HDMI and no Dolby Atmos support, but it does ship June 7th. Sonos also announced its voice control service will launch next month, which lets users control music streaming on Sonos speakers with built-in mics. All right, let's talk a little more about Meta's mixed reality strategy. We've heard about Project Cambria before. Meta has now demonstrated it in a video, although they blurred out the form factor because it's not ready yet, so they didn't want you to get any ideas. It's kind of weird that they blurred it out, but they did. It is the follow-up to the Quest 2 that's supposed to launch this year. It's supposed to launch by the end of the year. Sarah, what did we see? Well, so Meta CEO Mark Zuckerberg shared a video. We didn't really offer much, honestly. I mean, kind of look cool.  But yeah, as you said, the headset itself was pixelated out. It was a teaser video. That's what it was. What we do know is Cambria is a VR headset that is going to use its camera to use pass-through color video from outside and blend in virtual objects. Now, if you're not familiar with VR headsets, this is something that has been done before, but you know, we're still in the early days of this. Protocol has seen how it works and says it's not photorealistic, but it's akin to decent quality home video, say. So definitely a step up from the Quest 2 for anybody who's familiar with that. Cambria's image sensors are also higher resolution. And that allows for better better object separation. It also has an active IR projector for accurate, accurate depth sensing. Now, content and apps are created on something called the presence platform. Access to presence is being added to the Quest SDK. So mixed reality could and will be cross developed to the Quest 2. But that'll be added a lower quality than the Cambria because they're just different headsets. It's positioned for professional work, you know, support for virtual monitors, that kind of thing also might be usable for fitness. In fact, Zuckerberg said that specifically. And I would say that would be especially if the headset could be designed to use outside because the Quest 2 is very much not. All right. That because the Quest 2 only offers a grayscale view of the real world. You can get a view of the real world, but it's very blurry and gray, right? Yes, it's very like silence of the lambs. Like when you watch it, you're like, okay, I can kind of see my room. I'm just going to like, you know, make sure that my room boundary is okay. There's not much else you can do with it. And it's it's somewhat of a disconcerting experience when you're in there because it's like, they even have like a kind of like a low rumble when you're using the grayscale video like because it's meant for boundary setting. It's not it wasn't really designed. There's nothing really more to do except kind of make sure you have your bearings and know where you are. So you can use the presence to create something for the Quest 2, but it's going to be a little weird, whereas it obviously Project Cambria is going to be good because it's color and it's high res. Well, it's going to be better for sure. So yeah, so Zuckerberg also announced that there was going to be a demo mixed reality app called the world beyond downloadable soon and Quest 2's App Lab. So, you know, people can play around with it. The app was mentioned kind of in passing, honestly, at last year's Connect conference. So obviously the company's been working on it for a while. It seems like a way to explore what mixed reality can do on VR headsets rather than doing a whole lot itself. And as you mentioned, there are other mixed reality headsets that are blacked out VR headsets that do pass there, right? Yeah. So Meta expects Project Cambria to ship sometime this year. Sounds great. But you might be listening to this insane, but other companies are doing this already, right? Yeah, like Project Barjo, the XR3 similar headset already available, also tailored for things like training, engineering, medical research purposes, very much still not in a consumer bucket. But it doesn't mean that we can't get there. So what I find fascinating about this number one is that like Loki, this is a pretty important product for Meta. You know, Palmer Lucky, the founder of Oculus has I think correctly said that when Facebook bought Oculus, Oculus became Facebook, there's a reason why they changed their name to Meta and not something else. They want this to be a hardware hit for them in the way that the Quest 2 has been, in my opinion, the best of breed in terms of commercial VR. I'll say this though, I thought that teaser was bad. It was terrible. I don't think that it made that platform look interesting. I don't think that it gave any kind of real world context for what you would want to buy on there. I think that game looks kind of silly. And I personally think it is only designed so Zuckerberg looks more human, which is a uphill climb. I don't know how human people I this this is this is meant for the enterprise. So it's probably not going to hurt it because you're going to sell this thing enterprise. Yeah, that's what they're saying. They're like, this is for the workplace. This is for the enterprise. They're going to have other consumer follow ups to the quest. I know we called this the follow up to the quest, but follow up the quest in technology. This is going to be pitched for for uses in the in the workplace. So the demo that includes the Kmart, Lilo and Stitch creature running around your floor. That's what's so weird about that demo. I don't think the demo hurts them because they're going to sell this hand to hand. But it certainly didn't advance that notion. Did it? I was not impressed. I love the question. And I am a huge, huge believer. Same, same. I use it all the time. But I don't know that this this was not something that that part of you buoyed my spirits. And I'm always come coming from the consumer perspective. And I know that, you know, that the use cases of this are not always consumers. In fact, very much more enterprise. But I was sort of like, okay, okay, if the if the pass through video can be a little bit more real world, right? Like, not not the best, but better than what I have right now, I could, I don't know, do my workouts outside and feel a little bit more like it is, it is a real thing, rather than something that, you know, I put on the headset and now like the real world around me doesn't exist anymore. Both are fine. But they're different experiences. Just one last very quick thing on this Facebook needs this to be a commercial hit.  They want this to be a commercial hit. They want to go diversify themselves from the game they're in now, which is effectively what Google is doing ad sales and make it a little bit more Apple. For that, they need this to be more iPhone than Google Glass, which right now they need the quest to be that not Cambria. I think Cambria is a new part of the strategy. Cambria is a new part of the strategy, which is let's get a high end business use case, and then we could trickle it down into the quest, they'll have follow ups to the quest and you're absolutely right about the quest. But that doesn't mean Cambria has to be a consumer. Yeah, right. Yeah, I'm not saying Cambria specifically. I mean, this higher genre. Yeah. Well, let's talk about Microsoft's patents. Game rant. Notice that Microsoft had a patent published last week on a method for validating Xbox game discs for the Xbox Series S. The S is the one that doesn't have an optical drive. patents always use vague terminology. So it kind of goes all over the place. But essentially, it describes a system where you put the disc in another device, presumably another Xbox, maybe a Windows PC, and then you validate your ownership on that. It then describes all the possible ways it could transfer that game to the series S. But among the ones that seem possible are validation with an Xbox live account, and then you download the game to the series S. I think that's the one that most people would find compelling. There was also live streaming from one device to the other. That's kind of something that's already sort of available. And one intriguing bit about downloading the game from the disc to the series S over a land so that you weren't using your internet, you would you would actually legally rip it from the disc to your series S. One of the, I think the best parts of the patent described is the need for the system. Like what do you need to make use of this? Microsoft wrote quotes, many owners of physical video games, Mia have emotional attachments to their physical video game media. These owners simply appreciate the feel of handling the physical video game media and were the nostalgia associated with the physical video game media. Moreover, many of these owners view their libraries of physical game media and paraphernalia as valuable collections, similarly to rare coins collections were baseball, baseball card collections, etc. So they're going to make NFTs out of them. Yeah. I don't know where they just want people to still buy physical media. Now it's kind of crazy that how much about the feelings are in this patent? Because let's forget about arguing whether this is actually patentable or not. It actually hasn't been granted yet. Maybe it won't be, but it probably will be. Microsoft went to great lengths there to be like, we care about video gamers. And that that is why we would do this. Because video gamers have aged into their prime spending years. And if they can sell a big super deluxe copy of a game that has already been purchased probably three times by some super gamers, but this is the super elite deluxe version, then they will do it. And they just want to make sure that you are able to authenticate it and play it even if they come out with a diskless option. But yeah, look, all technology, I think this was a fascinating thing that we saw with the iPod being discontinued and then becoming a gigantic seller as Apple burned through their remnants, just by saying that there was going to be no more all of a sudden, all of the nostalgia that comes back from people living their formative years with these gadgets come back and you realize, oh, I got some extra money. Let me buy one of these last things. Yeah, it feels overly complex. I mean, we we've seen EA Roger was reminding us earlier today that we've seen EA and Blizzard do versions of this where you can just register your game and then it's stored in the cloud for you. You don't have to have the disk anymore. Voodoo has been doing a thing where you can pay a little bit of money and register your DVD to your cloud account and have the movie there. In none of those cases, do you actually need to put the optical disk in a drive? So but that's part of the experience, right? That's that's what that just the same way that you open up your baseball card collection. Yeah, the Greek of the plastic part of that tactile experience. Well, if you want to discover more tactile experiences, you can get ideas from people in our audience in our discord, which you can join by linking to a Patreon account at patreon.com slash D T N S. Hey, Tom, do you remember September 2021? Mm hmm. Yeah, I do. Well, Texas passed HB 20 a law against the banning demonetizing or otherwise restricting of social media content based on quote, the viewpoint of the user or another person and quote, and that kicked off lawsuit. Indeed, indeed it did. Trade Association called net choice has sued Texas alleging that law violates the US First Amendment protection against the government abridging freedom of speech. And in December, a Texas federal diss district court judge granted a preliminary injunction against the bill going into effect until the court case was resolved. It was an injunction. It said, let's not apply the law until the case is settled. However, Texas appealed the decision to the Circuit Court Court of Appeals. And it was heard by a panel of three of the Fifth Circuit Court of Appeals judges. That's a normal way of doing things. You just you don't have all of the judges. You have a panel of three. So Wednesday, the Fifth Circuit ruled two to one to grant a stay on the preliminary injunction, meaning basically, we're not going to let the injunction go into effect, meaning the law goes into effect instead. Now, a lot has been made of statements by the judges during deliberation. One of the judges said that social media platforms weren't websites. Another tried to compare social media posts to phone calls. There was a lot of talk about common carrier. In the end, as much fun as you may have batting those comments around, it doesn't bear much on the case because the court did not rule on the merits. They're discussing the merits when they say those things. They did not rule on the merits. They didn't even issue their opinion yet, although we will get that eventually. They just sent out the stay saying the preliminary injunction doesn't go into effect. But you just in live in Texas, tell them what this law does for you. Y'all HB 20 allows laws by private citizens as a remedy for violations. It's similar to some other more controversial laws that we have seen in Texas. So if a social media network with more than 50 million active US users discriminates on viewpoint, the state of Texas or any Texas resident can sue. Here's the actual text. A social media platform may not censor a user, a user's expression or a user's ability to receive the expression of another person based on the viewpoint of the user of that or another person, the viewpoint represented in the user's expression or another person's expression or a user's geographic location in this state or any part of this state. But bro, I'm also from Florida. Florida has a similar law SB 7072. But with the US District Court for the Northern District of Florida granting a preliminary injunction against that law, while a court case also from net choice challenges it on First Amendment grounds as well. So how are these cases going to go in the two most Justin Robert Young Union? Yeah, so we have conflicting decisions on the injunctions. We have the laws seemingly opposed by legal precedent and federal statute. Keep in mind a few of these facts. These are those facts that you can now say you know when this comes up in the future. In 2017, the US Supreme Court ruled unanimously eight to nothing with one abstention one recusal really eight to nothing in a case called Packingham versus North Carolina, striking down the idea of a state government putting limits on social media. There had been a North Carolina law passed prohibiting registered sex offenders from accessing commercial social networks. The court ruled that the law was unconstitutional because the state was attempting to restrict lawful speech. This is the decision in which the justices referred to social networks as the modern public town square. That opinion was written by Justice Kennedy and a concurrence was written by Justice Alito. The Florida's judge referenced section 230 of the CDA. That's the other thing. So Packingham is one legal precedent. There's also a statute that was referenced by the Florida judge when the preliminary injunction was issued saying that section 230 would seem to prohibit this law from going into into place. Section 230 specifically says any action voluntarily taken in good faith to restrict access or availability of material that the provider in this case social networks considers to be obscene, lewd, lascivious, filthy, excessively violent, harassing or here's the key part otherwise objectionable. If the platform finds it otherwise objectionable, they can limit it and they're protected by section 230 and they can't be held liable for anything that happens on their platform because of that. In other words, if a platform takes down content, it finds objectionable. Section 230 protects it from being sued for making those decisions. Exactly what the Texas and Florida laws were trying to make happen. Sue them for making decisions about taking things down. They found objectionable. So all right, let's talk about what might happen next. And you would think that the chaos is the point in this in the case of both these laws that they want these companies to change their ways because they're afraid of dealing with the static whether or not it is legally in bounds. So if there was an opinion from the Texas circuit, net choice could bring a district split decision to the Supreme Court where the two districts in this case, Texas and Florida have ruled in conflict with each other on a similar issue. However, the fifth circuit is notoriously slow in bringing out its opinions. So net choice may not want to wait. Net choice could ask for what is called an unbunked review of the decision where all the judges of the fifth circuit, not just the three judge panel review the case again. However, it's not necessarily likely that they'd get a different decision when they ask the same people. Another option would be to appeal the ruling on the injunction directly to the Supreme Court. The idea would be to get the Supreme Court to review the case on what's called the shadow docket, which means they review the oral arguments. This is done rarely in cases that might cause large disruptions if a decision is delayed. But the opinion may not come fast if they go that route. And don't forget this is all about injunctions. The main cases still need to be decided. If the Texas case and the Florida case ultimately come to opposite decisions, the outcome would then need to be settled by the Supreme Court at oral arguments. Tom, legal scholar, though you are, how do you think that would go? Yeah. So this is probably going to end up in the Supreme Court. It kind of looks that way one way or another. And so everyone's focusing on Justice Clarence Thomas who has previously indicated that large tech platforms with substantial market power might be akin to common carriers. And there is legal precedent for requiring common carriers not to exclude legal uses of their service. But would that mean Thomas would uphold the Texas law or even the Florida law? And would any other justices join him on that? That's hard to say. Thomas joined Alito's concurrence on the case that overturned the North Carolina law. So he'd have to find a difference between these and that that he found legally compelling. And in a another case called Manhattan Community Access Court versus Halleck, the court found that private operators of public access channels that are receiving government funds are not subject to the constitutional requirement not to abridge free speech. In other words, they don't have to abide by the First Amendment because they're private. That opinion was written by Justice Kavanaugh and joined by Justice Roberts, Alito, Gorsuch, and particularly Thomas. So both by looking at the precedents in the law and how the justices have ruled in the past, these Florida and Texas laws do not look likely to stand up. And in the meantime, right now it is illegal in Texas to moderate content based on the viewpoint of the poster that applies to Yelp, Reddit, Tinder, Facebook, Twitter, and more. Meaning all these platforms risk a lawsuit whenever they remove a post or otherwise moderate what's on their platform. Sarah, before we move on for this, does any of that make sense? Yeah, it makes sense. I mean, it's a mess. I mean, what I think I think we're dealing with right now is yeah, it's it's we're trying to figure out state by state how these things are going to play out. And yeah, it's very messy. I mean, and I think that the chaos is the point here, just to just to underline that again, what on the political side, the reason that these states put these laws in, is that what you're saying? No, no, I'm saying the mechanism by making this about suing and not making this illegal where the state is going to go seize a server or something like that.  Yeah, so so maybe just leave everything up just in case maybe maybe you which is exactly why section 230 was passed on a bipartisan basis back in the 90s was they're like, but if we leave everything up, that's chaos. This is all happened before, Tom, and it'll happen again. Indeed. Well, let's talk about black holes. Speaking of messy, you might recall the movie The Black Hole from 1979 scared me a lot when I was a kid. I don't remember watching 1979. I would have been too young, but I definitely saw it later. Anyway, scientific researchers using the event horizon telescope have captured a picture of a black hole at the heart of our very own Milky Way Galaxy Sagittarius A star as it's known or SGR A star is bending all the light around it, which is something that's already been captured by the black hole named M 87. That's something that researchers have have already done a lot of extensive research on, but they're very different black holes. Sags hole. I know it sounds weird, but it's a hole is over 1000 times smaller and less massive. And you might say, okay, well, maybe it's not a big deal. No, it's still really massive. It's measuring at 4 million times more massive than our sun. Although M 87's counterpart is billions of time more massive. So, wow, we are talking about quite a bit of space being taken up in space. The researchers developed new imaging tools, including a mix of super computer power to analyze and combine data and black hole simulations to help compare their findings, make sure that they knew what they were doing and they saw what they thought that they saw. The project took five years to complete factoring in 100 million hours of supercomputing time at the U.S. National Science Foundation. So, in other words, this is why you don't go to space. We suspected there was a black hole at the center of our galaxy for multiple reasons, but now we've observed it, which is a big deal because now we can find out that it's an everything bagel. Hmm. When you put everything on a paper.   No, thank you. Y'all let me know how it goes. You need them at the center of the galaxy, but stay at the center of the galaxy. Don't come out here on our spiral arm, please. No, even then. I never know. Even then, yeah, I mean, because we're taking pictures of it, we're taunting this black hole. I'm listening. You think it's coming for us? Yeah. I'm looking for full written evidence. It's a lot bigger than the sun. Like the sun is already very scary to me. I don't need anything else in the milky way. Our sun's like media. At what point in the movie is the protagonist rewarded for taking pictures of the great evil at the center of the universe? I don't remember. Consider that a writing prompt for your next sci-fi novel, everyone. Let's check out the mailbag. Let's do it. This one comes in from Doug regarding regenerative braking without brake pads that we were talking about in future EVs. Last week, Doug wrote in, there are many challenges, but the main issues are not about making regen braking work with stability control, et cetera. It's a problem of peak power absorption. So other than exotic sports cars, vehicles are capable of braking with a much higher deceleration rate than they can accelerate. What you're doing when you're doing regen braking is you're using the same electric machine that you use for acceleration. It's just in reverse. So think of turning the motor into a generator. All right. And there was some good stuff from Doug on this. Thank you for writing in with your expertise. Yeah. In defense of hybrid schedules, remember we asked people like, okay, if you like hybrid work, if you like being in the office a couple of days a week, staying at home a couple of days a week, let us know. Todd wrote, I like working from home. I like the flexibility of being able to take a break and do laundry or prep dinner. But I also like being around my coworkers. I feel like we have more productive conversation in the office in between people talking about football or their family. Some people will just never talk on Zoom. And when I'm sitting in an office with them, they have great ideas. Hallway meetings are better than Zoom meetings. Of course, my ideal schedule would be to have the ability to pick which days I'm in the office and which I'm at home, but we can't always get what we want. Thank you, Todd, for coming to the defense of the hybrid schedule. It's good to get that perspective. Well, thanks also to Justin Robert Young for being with us today. Justin, you're looking good, man. What else has been going on? Well, I'm heading out to Pennsylvania. So you can follow my coverage there next week on Politics, Politics, Politics as we come to the close of the primaries in the Keystone State, but also get a primer of exactly what's happening right now on the Wednesday episode of that very program. A third candidate has entered the fray in what was a two-man race, Cathy Barnett, making it a much more chaotic situation. So follow that, Politics, Politics, Politics. Excellent. And just a reminder, if you have thoughts or comments on anything we talk about on the show, feedback at DailyTechNewShow.com is where to send that feedback. Thank you in advance. We love to hear from you. Also, want to extend a special thanks to Travis Falstead, who's one of our top lifetime supporters for DTNS. Thank you for all the years of support, Travis. Thank you, Travis. Appreciate you. There's also a longer version of the show called Good Day Internet. If you know about it, you know about it, but it is available at patreon.com.dtns. Please join us if you can. We're live on this show Monday through Friday at 4 p.m. Eastern, 20 Honey, UTC. Find out more at DailyTechNewShow.com.slive. And we're back tomorrow with Shannon Morse and Len Perralter joining us. Talk to you then. This show is part of the Broad Pants Network. Get more at frogpants.com.


Hi everybody. We did it. Another five-star break sold out and ready to go. This is pick your team number 12 2021 tops five-star baseball. Great product here and we sold it out straight up so I appreciate everybody getting into the action. And we've got another case loaded up already if you want to get into it. Monday the 15th. Appreciate everybody getting into pick your team 12. No Rocky so we didn't sell them. And there's Rosario. Last Vodmojo Toronto Blue Jays. Thanks everyone for making this happen. Let's see what we got. Good luck everybody. Love this stuff. And we've got plenty of time to fill and run another one of these tonight if you want to. We'll use this king of diamonds right here to slow play some of the hits a little bit. And there's a redemption on the bottom here too. First one out of the gate. Davy Garcia, rookie autograph for the Yankees. Speaking of rookies, the rookies of the year were announced in the NL, Johnson India for the Reds, in the AL, Randy R. Azaranya. And the redemption, congrats. Someone is due to receive a triple autograph? A triple autograph of, looks like they're all the same team. San Diego, Seattle? Wow. Wow. Randy Johnson, Ken Griffey Jr., Edgar Martinez, triple autograph. That's James with the Mariners. Got the Mariners straight up rewarded with the triple auto. Congrats. Who do you think's holding up this triple auto? Who do you think didn't sign their cards in time? Maybe Edgar? Ken maybe? Randy? I mean, all busy dudes. I'm sure they're doing a lot of stuff. All right, good way to start the break. Remember folks, we got more of this in the store, jaspyscasewrakes.com. Check it out. Next, the marketing's Randy's holding things up. Oh, another redemption. Let's see what we got here. There's the egg, Dennis Eckersley, 38 out of 50. Yes, I do. So get your response. Alifonzo, the Oakland A's, and the redemption. You are due to receive a base autograph of C, Cincinnati, Chicago, H, Chicago, White Sox, Garrett Crochet, base autograph. It goes to Howard in the South Siders. Next box. You got a Das Cameron, rookie autograph for Detroit. Nick L, little cat team mojo. And we've got a Ricky Henderson, 33 out of 40. The man of steel. Nice. And that'll, that's another Oakland A for Alifonzo. Nice silver signature. Silver six, silver six. We got Lucas Geolito for the White Sox. Nice. Another one for Howard. Another White Sox. Lucas's teammate, Jose Abreu, Golden Grafs, one out of 25. Nice. Another four boxes here. Next two autos we've got Tariq Scubble, 28 out of 50. And that'll be for Nick and the Tigers. Yes, it will. Tanner, so grab your spots. And nice Cabrion Hayes. Pirates, that's gonna go to Martin. All right, three more box to go. Next autograph is Max Kepler, taking it to the Max. And that'll be for Howard in Minnesota. And then we've got Jordon Alvarez, 33 out of 50. Alifonzo with the Houston Astros. Two more to go, ladies and gentlemen. Good luck. Fingers crossed. We got a Jock Peterson, Cubs Edition. Jocktober. And that'll be for George and the Cubbies. Next is a red, three out of three Joey Vado for Jack B. Got a plate of the whistle, Jack. Jack's like, have you even pulled one NL card? Here it is for Jack B. And the Cincinnati Reds, a three out of three pentamorous penmanship Joey Vado. Plate of the whistle, boys and girls. There you go, Jack. Thanks for grabbing the reds. One of the last teams picked up as well. All aboard the Big Hit Express. And the final box. Good luck. It worked, yeah. Sometimes it does. All right, we got Sixto Sanchez, Rookie Otto, one out of 15. Nice low number there for the fish. That's going to go to Oliver and the Marlins. And the last one here is more White Sox. Wow, Eloy Jimenez. Howard with the White Sox. And there you go, boys and girls. Another great break of five star baseball in the books. I'm Joe for jaskiescasebreaks.com. Thanks for watching. Thanks for breaking with us. We'll see you next time for the next five star break. Bye bye.