Okay, I think I'm that up. I have no clue if this is actually working though. You can actually hear you're not Audio is fine. If anybody's actually watching you really likes pop-ups pop-ups All right, is it we're watching actually All I'm doing so Expect me to be like this for a little while That's really third monitor All right, I think I'm just gonna go and get started I don't know if anybody's actually watching this or not Actually Right stats or something. I don't know what's wrong But I'm just gonna get started today. I'm going to Mess around with awesome not really the first time that I'm messing around with awesome I've changed some Key bindings and added some wallpaper and stuff. So at least not a complete new but the most part I've not experienced awesome Reform So think like I said, I'm just gonna go ahead and jump in if audio is not good I can actually sit in the chat. I will try to fix that Honestly, I just completely guessed normally when I record my videos I record simultaneously and OBS and audacity that way all my audio is in audacity and I can Now watch the waveform up there with this I'm just gonna have to Hope the OBS manages to make this audio sound at least, you know, a quarter of the way decent Anyways, I'm gonna go ahead and jump in so this is What my Awesome looks like right now and the only thing I've like I said the only thing I've changed is a few key bindings and the wallpaper I've also I've also added some auto start programs So I think actually what I'm gonna try first is Finding some Races to kind of go by because I don't spend as much time on Unix porn as I used to be so the run prompt is super R Which is gonna be changed as quickly as possible because this is not D menu or Rolfi And I have to type out the entire word and the text is so small and we're just gonna Go to Unix porn Awesome is insane in terms of customization I remember seeing quite a few rices back in the day when I was you know, big guy going to Unix porn quite often of What? Awesome could you know handle I'm not going to reach that level of customization. I'm a horrible ricer as anybody who's watched my videos knows I think that's why this will probably work better as a live stream Then as a video because you guys can see without all the editing that I do To make those at least some way decent I mean, I won't go so far as a decent so Really what we can expect today is just colors and I'm gonna get rid of this title bar thing because that's No, no, I'm just not gonna keep that All right, let's search for awesome and Searching X porn here. We'll zoom in so again people can actually see so like is this menu over here Is that like Rolfi or something? I'm actually sure so he has a weird angle on his windows this person's windows Kind of reminds you of like When they do a fake UI for like a TV show or something, you know how they all have those like Squared off corners weird the weird things kind of reminds me that Hello, F society have hello Torsten. I said hello to F society. Hello You've got a shout out Do with it what you will and see this is something that I could see myself doing but I'm not gonna I don't want title bars this I mean Why would somebody want to emulate windows? That's another thing that is gonna be a promise. I don't know any little at all It's been a while since I've done Dracula rice. We could drag. We could do Dracula. What do you think? Dracula's a possibility. So I'm gonna open that up. Where was that right here? Dragons I did green with my DWM rice. I'm gonna be doing green All the recipes are really dark I know I can just see the small picture of them, but You seem dark Now see this is one of those ones there where they did crazy stuff rounded corners big icons and I'm actually not sure what that is. Is that is that I feel like that's Rofi Yeah, it's probably gonna end up being Dracula something simple There's no way I'm gonna end up doing this I first of all, I cannot get rounded corners to work on any window manager at all Even using the proper Pycom fork. I can't seem to Even get close to getting to work things always bug out on me. Let's see here This one here. I voted earlier. Well, that's really purple, you know Awesome has a ton of stuff that you can do with it from what it looks like I'm never gonna reach that level of functionality. I don't think First all right before we get it going any further. Let's see if I can find the awesome When a manager documentation awesome window manager.org documentation. All right Zoom in if I forget to zoom in on something and you catch it Give me a shout in the chat And I'll try to fix it because half the time I always forget to so this is just man page. That's Mostly useless. It has the default key bindings Awesome is customized by creating an X RC Lua. Okay That doesn't help me with all that bunch. I think something like mod s brings up the Key bindings, right? But I'm not sure what terminal this uses Does this use your default terminal set in the RC that Lua if so I should be able to do No, what I want to make that text bigger. All right, you know, let's go to two let's zoom in here and Let's see CD.config awesome Let's see here Vim RC.Lua so Let's see what I want to see is the what terminal I have set I Should have audacity or not audacity. That was dumb. Alacrity set is the terminal. I think it's down here somewhere Yeah, right here. I need to change this editor here to invent And we got Alacrity set here Terminal-e or editor. So that's the editor command Oh, it was another thing that I changed that I forgot to mention that I changed it so that the tile layout is Default and move floating to the end I wanted to use a floating window manager. I'd use plasma. All right, so that mod s thing that it shows shows Not in a terminal. It looks like it's just a function of something else. Let's see here Hot keys Hot keys pop up. So it's an external thing that it's calling an External library whatever it's called So this must not be using a specific terminal at all. I Wonder where you can change that Enable hot keeps help widget for them and other apps When require when client with a matching name is opened. Oh, that's right. That um when you hit mod s It actually gives you them hotkeys like over here But I want to know what terminal this is so it kind of make the text bigger That's because annoying it goes away when you press the mod key again, which It's just gonna show me that I'm never gonna use that So awesome rc man page I'll have to say that this this this documentation is very disappointing Alki Larry. Yes, I'm using alacrity all the time now I'm gonna do a video on it eventually but spoiler alert. It's fine. I miss termite mostly because termite is just simple and the Configuration file is simple. So I don't feel the need to go in there and tweak things all the time I Honestly haven't done much in terms of configuration for a lack of day. I need to get into that before I go through and actually do the video on it But yeah, I'm using alacrity. I can uh, you want Proof there you go alacrity right there Yeah, and I'm doing that in all my window managers as well The only one that I haven't changed to alacrity is bspwm. That's because I don't spend a lot of time in bspwm After my racing video. I kind of left that behind. I'm not I've never cared for bspwm because it's more complicated than I care for That's just me being eternally eternally lazy Yeah, I'm looking through this Documentation so far. I've not been Awesome client man page and that's short too. Okay um So the documentation for awesome is horrendous This is I mean all right, so I don't know if any of you guys know this but if you go to bspwm's documentation You'll find that that is just as bad But and even this is actually kind of better than what awesome just showed me Because this actually at least shows you some things that you can do and what awesome does The most information you got from the awesome documentation was the key bindings so Yeah, not the the awesome documentation is not going to be any help, which is Disappointing I know a lot of people who use the xfc for terminal torsten It seems to be the probably the most popular of the I know it's time to call it a graphical a graphical terminal But the one when anybody has one that comes with a a desktop environment A lot of people obviously also stick with gnom terminal Whatever floats you boat really on terminals It's a personal thing. I think I tried kitty I did a video on kitty. I was not impressed with it. I think it's because I was not happy with the way they Like had the accordion thing in them with their settings I don't know whether or not it was just because I was too dumb to know how to navigate it But I might give it a try again because I mean, I know a lot of people like kitty supposedly district tube said it was um fashion alacrity I'll be honest with you I have not noticed a huge difference in performance between termite and alacrity But you have to remember that I don't run complex Applications and scripts in my terminal. I'm why don't I need to get away from this bwm before I get confused I still haven't chosen a Color scheme, but I'm still thinking about it I Have one vote for dracula Dracula is probably a good idea because I know it so well and it went using that and like my vim config my new vim config actually wouldn't go through and um Hurt me all that much because it would kind of jive with the other color schemes that I use but I don't know it feels cheating just to do dracula because Normally what I do when I choose a color scheme I do this vim color schemes And then I um Of course, I'm not I might have to go to gbang So the one that I usually use is this one here And this just has dozens of color schemes to it for vim So this is usually weighted the um Last one I chose what for q tile was this one half This one here and I tried to do the the white theme and that did not work out. Well Uh, I don't think I'm going to try to do a white theme today But I don't really want to do the same thing. I already did What does this one look like? Does this have the list of the colors? That has a list of the colors It doesn't that's actually really kind of cool though. I wonder if I could easily get the codes Let's see here. Let's see if I can if I can find this. I mean, this is kind of like Purple is kind of dracula, but I don't know Look at the I term two colors here So that might be able to give me the actual color codes I I term twos Syntax is not the same as everybody else's so that's not gonna work That's disappointing. What else you got colors here? So we got color codes here, but They're not labeled by anything but number And that's not gonna help me at all Because I kind of need the names So to know what I'm talking because I don't know what color two or one at oh four is Like I'm pretty sure 255 is either white or black and the other end is you whatever So it had to be white because zero is black Right, I don't I don't use those color codes all that often Okay, so space bins not gonna work Uh sunbather. What's this one minimal? Oh pink is really pink. Do we have color codes? No, of course we don't what are the what do the colors look like? Listed here. Oh, we have Yeah That might work Do I want to go pink? You know, it's just that's just kind of to Dual colors, right?  All right, I'm gonna spend half the stream just figuring out how Many or which colors came to use Centrelating television, right? Two fire watch. What is this? That looks like one dark I mean done it I mean, could you I've done one like That I can't talk I've done one dark before many times and that one half dark is basically one dark as well Uh, yeah, I'm not what is This is basically one dark as well GitHub does got to Have you checked out Nord? I've done a Nord rice one of my first videos Was a horrendous i3 racing video where I did a Nord rice for i3 it um It was a horrible video as I mean my videos have gotten at least a little bit better since then but um Yeah, I've done Nord once before So we got votes for Nord and Dracula on the chat Old tech book does use Nord. Yeah, I know that I think every one of us is jealous of his accent If I had his voice, I'd have a million subscribers Seriously That guy can talk I'm gonna say this GitHub needs to do Uh images better you could kind of image it like cuts it all off. Maybe I'm just doing it wrong, but Show me the image Zoomed out or something. I don't know or zoomed in whatever Does this actually show the colors? No, of course it does it. What's this one? That gives me solarized vibes I would never do a solarized team. I can't stand that color scheme. I'm a little coyote. This one doesn't even I don't know. I don't know if I like the the dark on that one. Um All right, so here's Nord I like Nord All right Nord is one option. We're gonna I'm gonna open that up. But where the hell was it right here Do-do-do mountain here. What's that? All right. Oh, that's really dark That's not so it has three different versions I don't know if I like that like dark brownish whatever I'm kind of skipping a minimalist Do I have colors? No, it doesn't have colors not easy colors anyways Happy hacking. It's amazing how many of these are so similar. I know Nord and Dracula are too standard, so I'm trying to find something a little bit different This one is purple I don't know if I want to go that bright because it wasn't really bright with the idea with my dwm Rice last time But I also want to go so dark like all of these here are like really dark like this one here All right, I guess that's just basically basically Nord.  At least that's it for me Awesome, right? So this is going to be basically Nord as well People like the Nord I mean, it's cool it's a nice looking color scheme, but I'm looking for something different Let's see here. All right, so Why when you like this is not Okay, I'm calling bs They're saying that this right here is x-mone ad I mean really you can do that with x-mone ad That is surprising because I would I would have bet money That that is was awesome I guess that's the reason why it shows up when you search for awesome and and Unix porn.  I know that you can do anything with anything If you're gonna got the tops for it. I just don't I just don't So here's a stream idea. Let's watch matt check his phone for like five minutes straight.   I should have chose this before his hand, but I wanted to kind of do it all on stream Where was all those again? um, but I tried this x-mone ad config and it's cool, but I can't edit it I can't edit x the x-mone ad config can you know stock. I can't understand haskell for the life of me Just is completely over my head Like it took me ages and ages to learn to see To the extent that I've learned to see I don't know that I could ever go through and Learn haskell it just it just feels like it's completely Beyond me. That is a completely white theme Hybrid material, um That one. Oh, that's another weird colored one scrub box Gotham That's kind of cool Do we have colors? Oh, we do Sweet Has the color palette That's definitely an option. That's kind of cool. It's a little dark What's going to be funny is I've spent so many so much time going through And choosing a color scheme. I haven't even dived into the Configuration file yet to actually know whether or not, you know I can um Actually theme this thing It's possible that uh lua is beyond me too I mean You know something I'll I'll point out later Is that lua has a weird thing with comma so you can put commas wherever you want in lua apparently because it doesn't matter From what I've noticed, I Let's see if I can show you that Like some of the mod keys down here some of the key bindings if I can find these So some of these have commas within the curly brackets. So like this mod key comma Some of them see if I can find an example. It doesn't um Like this one here exactly the same no comma What the hell that's not the way programming like works Commas are supposed to be I mean the thing about programming is it's always consistent at least in my experience I mean, I'm not a programmer but for the most part You know commas have to go where they go semicolons have to go where they go and you know You can't vary those things but it just for whatever reason in lua you can if you put a comma here It would still build and work perfectly fine So I don't know what's going on with that So this one here, um Do do do Let's see. Which one was that? Well, that was um hybrid material. Was that it? No, that was the wrong one What was what was the one that I clicked on? Gotham Yeah, Gotham. I mean first of all Awesome name because we all know Batman's the best Which fin color scheme am I using like right now? Um I think that this is paper color That's why I think this is this is paper color because paper color is the one that I used for um My dwm rice It's a good color scheme I wonder actually if I can find It'd be hilarious if I end up just doing Paper colors this one here Yeah, right here. It's not the exact one Actually looks nothing like the one I'm using So I have no clue of the color scheme I'm using This is the one I thought I was using this is definitely the color scheme that I used for um My dwm rice you want to know what? I'm just going to use this one. I like this color scheme a lot All right, let's close some of this stuff out here. We don't need it anymore. We're just going to go with it Narrowed it down to two so we got the um Gotham and we've got paper color which one I'm just tempted to go with this one because it's really good I could I could differentiate it enough for my dwm To make it so it doesn't look exactly the same because I could use the sign instead of the green Because I use the green for like the main color and my dwm I could use the sign down here as the main color. All right. Yeah, I think that's what I'm going to do all right After However long that was I don't even know how long I've been streaming. It's been It's been a bit um Almost 40 minutes already.  I don't think I actually went live that fast, but Still took me ages to pick a color scheme. All right um So let's go ahead The first thing we want to do is get rid of the title bar. The title bar has to go away. So let's search title so Actually before we before I go through and do this what I'm going to do is get out of this and um Make a copy of it so cprc.lua into rc.old That way if I mess everything up and delete something that's important I can go through and just revert because goodness knows I'm going to make something I'm going to mess something up Guaranteed Let's go ahead and then back into rc.lua and then we can Delete this part here and then Title all right. Let's see here we can we can delete to here Yep still title bars Awful title bars. Yep, and to here I think yeah Okay, I think that's it Yep So if we save this and we do super Control r I believe um, all right, so I'm gonna Take my life in my own hands here and Reef start awesome while on stream Hopefully the stream does not go away because Sometimes the recording in OBS goes away when you so So Still going still here and the title bars are gone. Whoo. All right Yeah, all right That's great It looks so much better already. It looks like a real window manager I mean really could kind of stop there and I'd be perfectly happy All right. The next task is colors now.  Actually the next at the next task I want to do is change So themes define colors icons and font and wallpapers so define default slash theme lua Hi, zany. How you doing buddy? Yeah, youtube's notifications are horrible not as bad as facebook's notifications though since facebook went to their new Design, you know pretty design their notifications. They're god awful Yes, I'm one of those fools who still use facebook I think it's bonus because stubbornness because I've been using facebook since 2004 And I don't want to leave it behind. It's been it's a crunch. How would I survive without my friends?  What friends? What was I doing I've forgotten I've lost my train of thought. Oh, I was I was talking about this thing and I'm bemoaning The lack of documentation for awesome The lack of documentation for awesome is it's horrible and it's going to hurt me because I don't know like Can I just store if if I open up If I cd into dot config awesome again If I create something called theme dot lua, what am I supposed to do with it?  So awesome does have documentation well Seriously, they need to not hide that hold on a second We go to awesome when I'm just curious now Oops not download. That's not what I was looking for. I wanted the documentations here so So the two links that I didn't click on that's where the freaking documentation was So I would like to take this moment to solemnly apologize to awesome window manager for um Been moaning the lack of documentation when I was just too dumb to click on the right links All right, we can close that then So this is the default theme file if you wish to create a custom theme which I do copy this file To my theme dot lua and replace Okay, so this is the default awesome theme We're gonna copy Copy copy copy copy copy pasta All right, so what it is we so we had to Save it in Yeah, all right, so Touch my theme dot lua Okay, and we're gonna them into my theme dot lua And copy and paste this Okay, and we're gonna save And then it said to I don't know the key combinations So we need to change this to my theme Dot lua All right, we're gonna write And we're gonna see what we get when we Restart awesome Yes, and I don't know anything about lua either as You're about to see All right, so mod control r And I have an error lots of errors Okay, I was just following directions. I swear That means when I copied and pasted something over that I accidentally got something over here. I guarantee it So let's see here. Um Awesome dot config rc dot lua I'm looking at the the error because I Closed all the errors on the main screen Um You probably can't even hear me because the microphone um 517 All right. Well, you know Yeah, you're gonna keep giving me errors 517 and 518 Line 517 518, but that's not the line I changed in rc dot lua and this Um So that can't be a line number Undo that Yeah, and all I did there was follow the directions Um, so that was a complete waste of Time I guess Yeah, I'm not I'm not sure what we're wrong there So what if we would have I just changed this to theme dot lua So that means there has to be a What has to be the problem is there has to be some kind of Let's go to the top here and let's go through and make sure that this copied properly I don't see any like glaring issues Because I thought when maybe like when I went through and copied and pasted, you know Sometimes when you copy and paste code it accidentally copy something like out here like, you know Weird But it doesn't look like it Replace get themes directory. Oh you want that? And All right, so Following directions not my forte. I'm just going to put that out there So it probably would have been better without documentation if I wasn't going to actually follow it So I'm just going to you know Copy and paste this Do um, where is this here?  Didn't get away from me. I know Less I know it's there. I just don't know how to read Reading is hard Words in order not the right order All right, um, all right, oops No, go away from me them Now we're gonna try again No errors Um, um, no more of changes, but that's was kind of to be expected Um Because it's the default. Okay, so that means we should be able to go through I want to move this to a different workspace. Just go to three I remember that key binding because at least that key binding is the same as every other window manager I ever used You need to replace the whole line. Not just the same name. Yep I got that now Just like I said reading not my forte Even if I could read the docs, why would I want to do that? If I read the docs properly, then I wouldn't be making all these fantastic mistakes All right So now that we've got this up here running We should be able to go through and change some of these Fonts so the first change just here the font to Like can I just do nerd font? Oops And then change just to like I don't have 10 or so Oh, wow And of course I If I press buttons, I'm like, uh, I just smashed the key buttons. Here we go um All right Yeah, I know Uh, all right. Let's see if that actually made a difference. So that should just make the font different Yeah, that worked. Good. We got bigger fonts Yeah, I don't think those were the happy little mistakes. He was talking about All right, so we got the font change which is good The next thing I want to chew is colors. So we let's um, let's go back here I'm going to take my colors and move them over to a different workspace so I can see them at the same time Just like answering a message Or Okay, so Let's see here some theme background normal I wonder Now does this actually go through and explain what these things are? Theme background normal so like So basically what I'm going to end up having to do is go through and just guess um Guess what these are actually supposed to be so like The background is that going to be like, um This background Let's change it and find out shall we so we want that to be This color here.  That's not the right key binding Just curious whether or not what that changes Oh That's really uh That's not I don't think that that's appropriate I think that's what I meant to do Okay, so that's the background of the inactive norm Theme foreground. So this is going to be the like the text color. Okay the um Theme background system tray theme bg normal So this is going to be the system tray is going to be this over here. Okay um border So what I'm looking for is what I'd like to have to be this color is Like the title Theme title bar. No, there's the title bar is what we just got rid of so we don't want that's not the thing I'm you know looking for Can use your own layout icons like this. Okay, so that seems fairly easy um So what is the background Okay, I think I got this Oops not 109 Oops, that's not the right one Actually gonna have to go through and get that color again now Yeah, there we go We're getting there success Yeah, I'm not bob ross even at all. I have no design chops at all. I could I always watch that kid that um Show as a kid with his you know happy little trees um but uh This is one of those things where you just realize that you don't have talent for painting at all um People won't leave me alone on the text messaging All right So we got that changed and I think why actually works Robin, how you doing? actually astonished that people are actually watching this So thanks everybody for watching just I'm just gonna put that out there in case I forget later on um Thank you everybody for everybody for watching especially if you've watched this far um You have the patience of a saint if you've watched this far All right, so we have colors Now the next thing I want to try is the bar Hi, so how do you change the like the widgets in the bar? So that's I doubt that that's done here. So this At least not all of it's probably not done here, right? So if we them into rc.lua Oh, I already have this open I'm three. Okay. All right, so we're looking for the bar Air handling I I've seen your airs awesome. I don't need your airs your airs honestly A lot of these I was thinking I could probably go through and comment a lot of these things out Yeah I can't help you if you don't know why you're watching this Robin because I don't know why I'm doing this So we're both lost um I'm looking for here is so we got the this is the menu part. I haven't tried Herb's loft torsten Maybe someday the name scares me away because it feels like it's going to be complicated But that's just me judging a book by the cover All right, so my launcher is Again, going to be just the um The button for this menu up here, right? Yeah my utils Okay, so here's where the bar is right here Right, so we're just going to have to go through and actually look at the documentation again Um, what was that was why bar? Qtile has great documentation Um, and they allow you to search for stuff So here's why box Is that what that was called was why box? Yeah No, it was called y bar a y bar I like Qtile a lot But I can't not just have Nine workspaces. I have to have 19 or 18 or 20 workspaces. How you doing john? People aren't leaving me alone So back to the the uh documentation here. I'm looking for why box Why box hierarchy? Add a widget to list to the list of widgets in which hierarchies should count their occurrences I don't know what that means So when in doubt when in doubt We visit distro tube And see what he's got Hello distro tube. Awesome RC that lua Choose your theme. So he has a lot of stuff in here um This is where he changes the tag names, which I don't need to do I'm perfectly fine with one through nine Uh tag list buttons. This is more for the tags A lot of the times when I do a a ricing thing I'll just take dt's Uh configuration and just you know Start from there, but this time I want to start from awesome like Just the bottom level of awesome Yeah zany, I know But the problem is I always have on my setup So I have two monitors, right? On one side On one monitor, I always have all of the stuff that just stays the same it just stays static and I have stuff on like almost every workspace And then on monitor one things change, but I always have stuff from like five or six workspaces So it's just it can't just be nine. I'd freak out F society I don't I've never found a way to add more than nine on q-tile I tried adding more because there's it's just a list right in the q-tile config. It's just it's just a list so I just Added another nine it aired out and when q-tile errors out Bad things happen Like I said torsion I go through and I have stuff on all like right now I'm using three on the main monitor And I'm using one three four five six eight nine on the second monitor, so Maybe if I had a third monitor. No, if I had a third monitor, I just want nine more workspaces Uh, hi Reese. How you doing? All right, so going back to what I was doing here. So this is his menu system my main menu What we're looking for in district tubes is the bar because I'm going to see an example of the bar which Oh, I could never live on one work if I Although I say that But before I started using window managers I lived on one workspace all the time and it used workspaces at all I just used monitor one monitor two and then the I had like all my windows stacked on top of each other like a crazy person All right, um still trying to find the his bar here. These are all his key bindings Default client focus. I could just search, you know, like a I could just search pattern found bar Here we go piano bar menu bar title bars So far I've not been successful with finding his bar. These are all title. He so district tube keeps his Uh title bars interesting choice Okay, so I'm not going to find his So why bar is not actually in his config so he must do his configuration here somewhere else Um, maybe he uses a different bar with awesome. Does he Robin has 60 works I mean, I'm a workspace hog, but that's just way too many I've lost things like Like and my computer stays on for, you know, a couple weeks and all of a sudden I'd like, oh my goodness I had obs open this whole time. I wondered where it was at Tags and layouts That's not going to be it. Yeah. All right. So district tube has failed me. I can't I can't find it libraries error handling setting a theme Um Okay, well So we know why bar creates text block create a text clock widget my text clock widget that widget box text clock so Where do I get the list of like widgets? Is what I would like to know I mean, surely I mean, we did find the awful ybox This only duplicates awful ybox, but not ybox y bar The module has been been depreciated And it's been renamed to y bar, which is where we just were Okay, so create a new ybox and create and Attach it to the screen. So that's what this does over here. Okay So widget is one of those things that it does theme variables Okay depreciated functions methods Y bar remove. I don't know what any of this stuff means Uh All right, man Zany have a good time Have fun I'm gonna keep Bashing my head against some lua here Other object properties All right I don't know how to do the bar DT didn't help We're just gonna have to go through and see if we can find someone else who's actually done a oops. That's the wrong one awesome That's what zero is for Reese Key zero is for 10 What I miss most about i3 is i3 has the ability to sign those key functions or key findings to Uh, every single workspace no matter how many you have see there torson Um My issue is that I can't do uh I'm trying to figure out how to add stuff to the bar And the documentation is crap Awesome copycat. Um, we're gonna have to look at that and see if that's some Some of these things are pretty cool Surely surely don't call me surely like just a regular rice. That's not gonna work And for just a regular old rice that has a regular old bar Exactly like that that kind of looks like dwm. I mean done it. All right, so where are your dots? I'm gonna steal your dots kind of Uh dot config Awesome awesome Rc. That lua Zooming in All right So we're looking for ybox Here we go Pattern found All right, so those of you who told me to switch away from vimium to vim vixen Are you looking for my ybox in screen dot connect for each screen?  I don't use firefox picture-in-picture Like at all, but I mean We could try let's go to youtube. Oh, we could do stream inception Let's see I actually have um picture-in-picture disabled so I can I can actually show you that all right, so that's you'll have to figure that on your own Um I think because I hated the little button Where was I? Create a ybox for each screen. Okay That basically apparently is already there because I have a ybox for each screen it ybox is there I just need to know where the hell the the like what the widgets are How can I add a widget or how can I add um? Like a script or something Thanks fs. Uh, thanks fsociety for science. Thanks for uh coming by Ybox is a container So let's notice what he's talking about Or he they talk about I don't know I think that's why I'm trying to find someone's example because I that's the best way for me to learn is someone's example and Them vixen is horrible because it doesn't actually highlight the thing that you search for well. It does but it's just Show high wide box and it doesn't show you the number of the thing you're on either So I don't know if I'm at the top and I'm at the bottom Back at the top. Okay Where's the highlight for this one? All right, so This is where the library is called. Okay Here's a function for if it's visible Okay, create a ybox for each monitor Show high ybox maybe I'm not Ybox is a container That holds other widgets I know I'm looking for an example where people call their widgets Because the documentation here shows Nothing with the widgets like what widgets are available Then vixen is okay. I've had I'm having my problems with but I think it's mostly uh getting used to it um like the the Documentation for ybox is not I mean like I don't care about the position right now. I just want to know how to um Like add a widget. I just don't know and This is typical Linuxcast right here guys Don't know what he's doing I don't know This is obvious title bar widget This is title so they use widgets in too many different places call Yeah, that's a good idea That's not what I was looking for Create the ybox my ybox equals my full awful ybox foreground Border color, but I mean those things are all great If I was just theming it Add widgets to the ybox order order matters Okay, here we go my launcher my tagless spacer my layout boxes Okay Layout equals awful widget layout horizontal left right.  I was just going to copy and paste that in there But that's a bad idea. I mean that's just Not a good idea I definitely get errors So we got like the Functions that wallpapers Awful tag manager awful widget prompt Tagless widgets, so that's all tagless a task list Which is going to be this thing up here Okay Create the ybox Position top screen ES add widgets to the ybox If you're talking about me Robin, I'm not from Gambia So this is so this is the left my launcher my tagless my prompt box And then s my task list so that's the middle middle widget right widgets Okay So if I have examples now and I found them right in my own Configuration file a question is where do I get the list of the widgets? Like what widgets are available? Are the volume widget? We know this let's try right here Let's copy and paste this But we'll see First we don't need to keep the keyboard layout. Okay, so We're starting Yeah, I didn't do anything imagine that Imagine my shock and surprises that did not absolutely nothing So those aren't actually widgets that you can use Those are from that vicious thing that where where did I see somebody using that vicious like extension pack Was that maxi on youtube So like this is like a um Okay, so This is just something you like this this has like a collection of stuff Vicious is a modular widget white library for window managers. Okay Please see our online documentation for details Uh, this is the nice documentation layout uses a lua a lua library I know that's why i'm here Listen to my own voice definitely. Um Yeah, I think i'm gonna end up having to look into this Vicious thing a little bit more Or i'm just gonna Completely steal someone else's rice eventually if i'm gonna stick on awesome for a while All right, the last thing I wanted to do today was because that's a complete failure Last thing I wanted to do was play around with the key bindings just a bit because the key bindings are trash Uh Where am I 8% I gotta go down Down down down Really if they were right there all along awesome that widget awesome that widget calendar client icon common text clock out so there's only like the clock in the task list And because I see the awful that widget here in the Yeah, I'm gonna mess around with that stuff later. I'm I've lost my Motivation for that for now uh All right, so I took a Yeah, that's what I needed to okay, so I need to go through and add a couple key buttons So I need to change First I need my the mod keep mod r needs to change and go away as far as possible away from me I'm sure I've passed it mod w Shows me menu. That's eventually going to show Firefox if I just stay in awesome that's going to show firefox s left right escape j k w jk jk u tab mod return mod control r mod shift q See my l h h l l h space n where the hell's r Ah, here we go right here. This is what I want. All right, so we need to change this to First of all mod d. Hopefully there's not another mod d commands And we need to change this to Function and we need to delete this part here and leave end. I think So we need to make awful util spawn Okay, so we need to do function open close awful That util that spawn open close Quotation marks And then See here. You got to get the right rofi Call for it. So rofi is this here rofi Dash show d run oops show icons font oops hack nerd font 13 and then end comma and would change this to rofi save this mod control r And we have errors because of course we do there's an extra Uh parentheses there somewhere so Where do we have an extra parentheses? Yeah, uh Extra parentheses somewhere. All right, so Mod key d function open close awful util spawn key d comma Function open close awful dot util dot spawn open Quotation marks rofi then the thing that I needed to do Okay First of all matt learn how to spell font 13 close the one quotation mark close the other quotation mark end parentheses the word end And a comma I don't see I don't see the x I think I'm gonna have to have to get rid of the the font part I had to do that in Qtile as well because qtile does not enjoy extraneous Quotation marks or the quotation marks No more of that crappy run prompt success with something at least Yeah, I know I got to use the sync quotes I I know that in my head, but I never do it because I'm a dumb ass It's just the way things work Yeah, it does zany unless I know that Uh, it doesn't matter This works Because you can actually control the font into the Rofi theme and I think I've done that so I don't even actually need to copy that But for whatever reason when I copy that out of my sx hkd Uh config file, I always just put that in there and then Because the sx hkd is much more forgiving in terms of you know quotation marks All right, so the other thing I wanted to check So we've got that done Is um Go through some of these other ones here. So some of these other Keybindings are just kind of trash Like because if I open up another terminal moving between them should be mod and like jk, which it is Why did I think it wasn't? Yeah all right so What I really want to do here what I really should do Is go back into my theme here because the invalid What now I don't know what that error was Uh Go back up here. I want to change the border color So the border color Is this one here? So Which is um Okay, so does Anybody know how I can check it change it so that when I refresh awesome.  It's in michigan awful that tag that view index. Okay view idx Yeah, I don't have that Unless I spelled it wrong, which is possible No, I don't have that Is this something I can add Put it at the end All the lua made mw switch to dw What I do is put the um One in the quartet in the parentheses Or do I have to keep the eye in there? I burp all the time Oops, I'm gonna trust you on that one Yeah, that worked. Thanks less. That was good Now do I need to do that per monitor? So if I wanted at the work for monitor two as well Would I just Add a two to the end like I don't know lua at all as you can as you've seen Numbers the workspace you want to open so it's going to open up on both workspace So I'm gonna try that again, so I changed just uh, I don't know three It goes to four That's a little weird, right? the number Of the workspace you want to open which I open in three and went to four so If I wanted to go to three, I'd do two, right? That's the way that works. It's weird Yeah, that worked out that way Okay, that's a little weird. All right guys, I'm gonna stop this has been going on for Hello a long time. I didn't get everything done that I wanted to do but I have a border here. I have a color here I have the title borders gone. I have the font changed I learned a little bit about the the y-box up there, but I'm still completely lost on that So I changed it to zero It would be All right, we're gonna try that I just changed it to zero. Yeah, because zero is one, right? All right That makes sense. It's fine It's weird, but it's fine Get him or I'm coming from dwm. So DWM doesn't have that functionality at all. You have to build it and log out log back in I mean, I understand there's you know hacky ways to get around it, but it's better this way Yeah, sorry Robin. I do have to go. This has got to stop Uh, but this has been successful. Um Maybe a stream a week I could do something like this every week. I don't know if it'd be ricing all the time I might just come around and chat Uh, but it'd be you know, it this was fairly fun Huh Yeah, awesome is not awesome Uh, I don't like lua I'm Coming close to say that I don't like lua almost as much as I don't like haskell But I think I need to spend more time with it and actually, you know Read the instructions Anyways, thanks everybody for who's helped me out in the the chat because I definitely got some um Help from there because I wouldn't you know I probably would have spent about three hours on that theme file because I didn't read the damn instructions So anyways, thanks everybody for watching followed me on uh Twitter at the linux cast facebook at the linux cast patreon.com slash linux cast everybody Thanks for uh, I should probably go there and thank my patrons while I'm here devon zack marcus american camp Thanks for your support. Thanks everybody for watching. I'll see you on the next one Stay safe


In the previous lecture, we started discussing about thin film dynamics and we started looking into the governing equations and the boundary conditions and we tried to identify that what are the boundary conditions for the free surface and in terms of the tangential stress balance and the normal stress balance and the kinematic boundary condition. Then we tried to derive the dimensionless forms of the momentum equations and let us go to the slide to summarize the various dimensionless forms. So these forms could be derived by expressing u and v, u, v and p in terms of the small parameter epsilon u equal to u0 plus epsilon u1 plus epsilon square u2 and so on. Similarly, v and p and these are the equations. The x and y momentum we derived in the just towards the end of the previous lecture and the continuity equation form is quite obvious that is this one. Boundary conditions, the bottom wall boundary conditions the bottom wall boundary condition is quite straight forward the no slip and no penetration and we will now devote significant attention towards describing the boundary conditions at the top wall. So the kinematic boundary condition how do we express it in terms of the small parameter? So let us try to work it out in the board as much as possible and then we will refer to the slides. So you have this is the kinematic boundary condition. So what is f dash, y dash minus h dash what is grad f dash where i and j are the unit vectors along x and y and y direction and x prime y prime directions are the same. Now let us simplify this. So to simplify this what is del f prime del x prime that is del h prime del x prime right because in f prime h prime is a function of x prime. What is del f prime del y prime 1? So this you can write h prime scales with h0 and x prime scales with lc. So when you write it in a dimensional form a dimension less form it is h0 by lc into del h del x h0 by lc is epsilon. So minus i epsilon del h del x plus j. So what is the normal vector? For getting the normal vector you also require to calculate mod of grad f dash okay. So what is that? It is square root of epsilon square del h del x whole square plus 1 to the power half. So what is n cap in the leading order if you divide this with this and consider that epsilon is a small number then what will be that? It will be minus i epsilon del h del x plus j plus higher order term because in the division this term will tend to 1 as epsilon tends to 0 okay when you divide this with its mod. So now del f dash del t dash so this equation this is actually the original form of this equation the kinematic boundary condition. Now del f dash del t dash is equal to what? Minus del h dash del t dash v dash you can write this as u dash i cap plus v dash j cap right where u dash and v dash are the components of the velocity vector along x and y dot with sorry this is scalar so this vector sign will not be there. So grad f dash is minus i epsilon del h del x plus j this is equal to 0. So now what is the scale of h dash h0 t dash is tc so h0 by tc del h del t plus what is the scale of u dash uc so uc into u0 plus vc into v0 u0 and v0 are the dimensionless 0th order terms for u and v dimensionless because no dash is there at the top and 0 subscript means 0th order so u equal to u0 plus epsilon u1 that because we are writing only the leading order terms. So as I am telling that these things this can be worked out by writing u equal to u0 plus epsilon u1 but now we have we are trying to be smart enough to like a predict what will be the form without always writing that big form expanding and neglecting small lower order terms I mean that kind of insight I mean as we practice more and more that kind of insight should come so that it saves some effort. So this dot with minus i epsilon del h del x plus j equal to 0 what is tc tc is yes lc by uc right so lc and the numerator you get uc so what is h0 by lc epsilon so minus epsilon del h del t plus uc you can cancel from both the terms if you cancel uc from here this will be u0i plus vc by uc is epsilon plus epsilon v0j dot minus i epsilon del h del x plus j equal to 0 require one more step in the camera picture board is almost invisible so I have to shift to the side so minus epsilon del h del t minus u0 epsilon del h del x plus epsilon v0 that is equal to 0 this is alright so you can write v0 is equal to del h del t plus u0 del h del x so this is like what is this like this is like the total derivative of h right so the total derivative of h the total rate of change of h is the v velocity component in the leading order that is what the kinematic boundary condition is giving so we will summarize this discussion of kinematic boundary condition in the form of the slide so you can see that we have calculated the normal vector so if you look into the slide as grad f by mod of grad f so then j minus epsilon del h del x i plus some term of the order of h square which is small so you can see that v0 is equal to del h del t plus u0 del h del x this is the kinematic boundary condition so we have expressed the kinematic boundary condition in terms of the small parameters using the lubrication theory approximation so this is one boundary condition next we will move on to the shear stress boundary condition so in the shear stress boundary condition see we start with the dimensional form so tau dash dot n this is what this is the traction vector in the dimensional form dot s is equal to grad s sigma dash dot s so we have derived this form earlier in the previous lecture at where at y is equal to h h is a function of x and time so del s we have discussed is known as surface gradient operator keep one thing in mind we have not written actually it would have been better if we are written here del s also prime because this is a gradient operator in dimensional form not dimensionless form but just for I mean simplicity in writing we have written it just like the normal grad operator but you have to keep in mind that when it is operating on a dimensional variable we are looking for dimensional derivatives that paradigm we should keep in mind so grad so now I will go through the slide because the algebra maybe a little bit more involved but there is an intuitive part of the algebra like I mean if you once you get more and more experienced in fluid mechanics you will realize that there is some algebra which without doing the bulwark you can get the essence of the algebra and that is through the scales and how you do that I will show you I mean that will help you to do the necessary algebra without doing too much of bulwark all the time so the surface gradient operator del s this becomes I del del x plus del del y into del h del x see this form this is like you have the difference between the flat surface and the curved surface because the curved surface h has a tangential direction that continuously changes as you move along the surface so for that to accommodate that you have the extra term so you had that del del x if it were a flat surface now here you have del del y but it is like a chain rule it is as if like del del y into del h del x where this h is a representative of the variation of the height of the surface as a combined function of x and y so it is it resembles a sort of chain rule del del x plus del del y into del h del x it is an operator that sort of gives the tangential derivative by considering that the tangential direction changes continuously because h is a function of x okay then the tau dash dot n dot s so first we note so we have got the n so it is basically you have to do the bulwark you have to make this tensor product of tau dash tau dash you can write that is the deviatoric component of the stress tensor so that is like mu into del u i del x j plus del u j del x i all those terms you have to assemble then n is the unit normal vector we have already derived what is n so that is what minus i epsilon del h del x plus j that is the n direction what is the s direction we have written i plus epsilon del h del x j how do you get it just let us try to quickly do this I mean these are all basically like vector algebra I mean nothing more than that but just in case you feel little bit uncomfortable I am trying to do all the hidden steps wherever possible so you had n is equal to minus epsilon del h del x i plus j let us say that s let us say that s is equal to a i plus b j where a and b are to be determined then what is n dot s dot product of normal and tangential they are orthogonal to each other so that is minus a epsilon del h del x plus b equal to 0 that means b is equal to a epsilon del h del x not only that s is a unit vector that means its magnitude is unity that means a square plus b square equal to 1 so a square plus b square equal to 1 means a square into 1 plus epsilon square del h del x square is equal to 1 that means considering this as much smaller as compared to 1 you have a is equal to 1 and if a is equal to 1 b is equal to epsilon del h del x so the s vector is i plus epsilon del h del x j okay so let us come back to the slide so tau dash dot n dot s okay so you can express this in terms of mu this assume that it is a Newtonian fluid you can express this in terms of see this is the stress tensor this is the unit normal vector this is the unit tangent vector you just make the product as it is just do the bulwark then when you do the bulwark you will get the corresponding dimensionless terms multiplied by a scale of tau okay so what should be the scale of tau I mean if you work it out you will get mu uc by h0 but you can easily get it from your common intuition like let us let us write this term so tau dash dot n dot s so this is equal to some thing into tau dot n dot s where this tau is the corresponding dimensionless form so tau dash what is the leading order term in tau dash mu del u dash del y dash right so mu del u dash del y dash it is corresponding scale is mu uc by h0 so you can you simply mu uc by h0 will come here okay so you can do that without I mean going through any algebra just the dimensionless form dimensional form and the dimensionless form they are related by this scale this must be true okay now right hand side you have the surface gradient of sigma dash where this is the dimensional surface tension dot s right so how do we get the surface tension gradient question is this so what is the scale of the surface tension gradient is it sigma by lc so let us try to look into that what should be it so to look into that let us say let us assume that the surface tension scales as sigma dash is of the order of sigma 0 that is sigma 0 is the scale of surface tension I mean typically we could have written sigma c but sigma 0 is the common notation used in books so that is why I have written this now that does not mean that the surface gradient of sigma dash will be sigma 0 by lc why for example let us say that sigma dash is equal to sigma 0 into 1 plus beta by lc plus beta x by lc this is a linear term then you can have a quadratic term cubic term etc. So you can tell that I mean are we just doing arbitrary mathematics what is the basis of taking variation of sigma with x like this so let us say that you have imposed a temperature gradient along x right let us say that you have imposed a t versus x linear because the surface tension will vary with temperature therefore sigma may also vary with x linearly if t versus x is linear. So this is a signature of sigma versus x linear so if this is a signature of sigma versus x linear then it is gradient with respect to x is beta into sigma 0 by lc right just differentiate this with respect to x this is the leading order term see in the surface gradient only the leading order term will feature in the lubrication approximation. So this will become so the grad s sigma dash will become sigma 0 beta by lc so these are the two things that we will remember so this we will note down in the board sigma 0 beta by lc let us go to the next slide. So you can write this is the remember this is the order of magnitude of this right so you can write mu uc by h0 tau dot n dot s these are all dimensionless parameters is equal to sigma 0 beta by lc grad s s sorry grad s sigma grad s sigma dot s okay because this is the order of magnitude of the term the remaining is dimensionless dimensional equal to dimensionless times its scale that is the form that is that we are writing so tau dot n dot s is equal to sigma 0 beta by mu uc what is h0 by lc epsilon so this you can write epsilon beta by mu uc by sigma 0 into grad s sigma dot s what is this mu uc by sigma 0 this is the ratio of the viscous force and surface tension force so this is called as capillary number a very important non dimensional number in the context of thin film flows viscous force by surface tension force so we will summarize this part through the slide so you can see the boundary condition equation 13 it is written here tau dot n dot s minus epsilon beta by capillary number grad s sigma dot s equal to 0 where grad s sigma dot s is equal to you can see that chain rule is used del sigma del x plus del h del x into del sigma del y so this we call this is the shorthand notation we use del tilde sigma del tilde is del del x plus del del y into del h del x okay this is the shorthand notation that we use now tau dot n dot s so if we want to evaluate that so tau dot n dot s so the algebra is a bit tedious I have put this algebra in the slide just to tell you just to convince upon you that for every work there is a bull way of doing it and there may be a little bit more tricky way of doing it so if you see here tau dot n we have found out so this is tau and this is n, n is minus epsilon del h del x i plus j right so the components of n are minus epsilon del h del x 1 this we have derived in a previous lecture then you have tau dot n so you have bent the dot product and then tau dot n dot s we have derived what is s also so if you do that you can come up with so many things ultimately in the leading order it is del epsilon del u0 del y now this you can say without any bull work because tau dot n dot s is eventually the tangential component of the stress acting on the surface in its leading order in a dimensionless form so tau if it was in a dimensional form it would have been mu du dy but now so mu into u dimension by y dimension so out of that now if you write it in terms of dimensionless parameter that mu into y dimension and y dimension by y dimension will be absorbed and it will simply become del u del y in a dimensionless form so this is a dimensionless form of mu del u del y okay so with all this algebra this is where you land up with which is which is quite intuitive so the boundary condition becomes that tau dot n dot s becomes del u0 del y minus epsilon beta y capillary number del t the sigma equal to 0 at y equal to h x t you can clearly see that if there is no surface tension gradient at the top surface then del u0 del y is equal to 0 that is the velocity gradient at the free surface of the film is equal to 0 okay so this is tangential stress balance so what boundary conditions we have discussed through lubrication theory kinematic boundary condition and tangential stress balance we are left with the normal stress balance so now we will discuss the normal stress balance this is the final boundary condition that we apply for our analysis before we can solve the whole system of equations normal stress balance so there is a particular note that we have put here and this note is important from a physical perspective normal stress balance is a bit difference from shear stress balance this is simply because while balancing the normal stresses we have to take into account pressure which acts always normally to the interface apart from this we have to include the effects of Laplace pressure that is the pressure difference across the interface caused by surface tension and surface curvature this also we have discussed in addition there is something that we have not yet discussed that we have this is the thin film when the thin thickness becomes very small ultra thin where intermolecular forces of interaction come into the picture then the van der Waals forces of interaction become important and that gives rise to and another additional component of a pressure like quantity which is called as disjoining pressure so that we shall denote that as p dash extra okay and I will show you that where in the mathematical formulation you put it now the disjoining pressure what is the formula and expression for that it is also a function of the film thickness it will typically scale with 1 by h to the power n where n is typically an integer so where h is the film thickness so with the film thickness becomes very small and small this will become this disjoining pressure term will become very very important now expressions for disjoining pressure how they are derived and all those things I mean that is basically within the purview of the theory of the molecular theory of like the corresponding interaction forces and I can refer to you a very good textbook if you are interested that intermolecular and surface forces by israeli israeli value it is a very authentic textbook you can intermolecular and surface forces so you can read that textbook to get the details of what it is but in terms of using it in the continuum approximation I will continuum formulation I will show you where to plug in that term in the thin film analysis so that you can work out that use that expression to work out a thin film problem so you can see here that p dash-p atmosphere-tow dash dot n dot n this is the viscous part that we discussed this is the hydrostatic component is equal to sigma dash by r plus p dash x okay now how do you get this r from n actually from vector calculus you can relate the radius of curvature with the divergence of the normal vector so this 1 by r if r is dimensional then this is the actually delta dash dot n delta dash as I told that we have not written delta dash in the slides so this is the dimensionless sorry this is the dimensional divergence so this 1 by r so now let us see that how we can put various scales here so let us try to put various scales so this term we have tried to simplify by usual scales so let us the final result is given here but I will try to see that like what form we get by putting various scales so p dash-p dash atmosphere-tow dash dot n dot n is equal to sigma dash by r dash or sigma dash by r r is a dimensional radius of curvature plus this one so p dash is pc into p right p dash atmosphere is pc into p atmosphere this is tau dash sorry tau dash is equal to tau c tau c is mu uc by h0 into tau dot n dot n this is equal to sigma 0 into sigma by sigma 0 by r into sigma right plus px is there so this different terms so you will get p-p atmosphere-what is pc just tell what is pc tell from your notes what is pc yes mu uc epsilon square lc so you multiply by or you divide both sides by pc so mu uc by h0 into epsilon square lc by mu uc into tau dot n dot n is equal to sigma 0 by r sigma into epsilon square lc by mu uc okay plus p p dash x into epsilon square lc by mu uc so now let us look into this term mu uc gets cancelled h0 by lc is epsilon so 1 epsilon gets cancelled right then here you can express r in terms of lc you can non-dimensionalize r in terms of lc so you can write rc so if you write this r in this particular form that is also okay but I mean sometimes we write r non-dimensionally we will see in the slide how we write r non-dimensionally but before that you can see that here also the capillary number appears which is more important mu uc by sigma 0 now to non-dimensionalize r if we define a non-dimensional r as r by lc or lc by r whatever then this will become epsilon cube or in other words depends on how we actually non-dimensionalize so better we will keep it in this form so this particular form is sigma by r into 1 by capillary number into epsilon square lc so you can make a suitable choice of the scale suitable choice of the non-dimensional r such that this epsilon square you can absorb through lc by r it becomes epsilon cube so that is what is shown in the slide but that is again it depends on the choice so you can clearly see here so how do you come up with the choice of a suitable scale for r how can you come up with a suitable choice for the scale of r so you have so let us write this as del dash 1 by r is equal to del dash n so what is del dash dot n what is del dash i del del x dash plus j del del y dash dot what is n j minus epsilon del h del x i so this you can convert del del x dash to del del x and you can convert del del y dash to del del y how do you do that so del x dash is equal to x into lc so i del del x 1 by lc plus j s 1 by 8 0 8 0 is epsilon lc then del del y dot n right so 1 1 by lc comes out there in this expression in that 1 by r so that lc will cancel with this lc okay there is a 1 by lc common you can see here that 1 by lc will cancel with this 1 and this 1 by epsilon this will go in the numerator to make it epsilon cube okay so if you come to the slide you can see that p minus p atmosphere minus epsilon tau dot n dot n is equal to epsilon cube by capillary number into del dot n these are all dimensionless sigma this is dimensionless sigma now how do you calculate the term tau dot n dot n and epsilon tau dot n dot n so tau you can express in terms of the velocity gradients the non dimensional velocity gradients n we have shown that how the n comes so tau dot n dot n you can see that it comes of the order of epsilon square so that is why see many times ignorance is a blessing in disguise as I have told earlier and again I am repeating see this term being of the order of epsilon square and this term being of the order of 1 actually it will not matter if you do not have this term because this will be of the order of epsilon square so fundamentally it will be wrong if you do not write that term but that term will not be a dominant term so and not only that del dot n so there is a del dot n why do we require the del dot n del dot n we require because you have this epsilon cube by capillary number del dot n so del dot n del is i del del x plus j del del y dot n is that minus epsilon del h del x i plus j so this becomes minus epsilon del square h del x square okay so then this becomes p s minus p atmosphere is equal to this so this is the expression that relates that is basically the previous expression where that del dot n is substituted so note that in the boundary conditions we have term we have retained some terms involving epsilon or higher powers of epsilon so you might argue that since these are higher powers of epsilon why have we retained this in the boundary terms this reason we have already discussed in the context of lubrication theory what is that reason the reason is thus these terms actually incorporate certain other scales which are yet to be determined like u c for example so look at this term so if you look into this term you will realize that you have the capillary number where you have mu uc by sigma 0 so in that there is a uc unknown so that uc may be as large or as small to make this term comparable to p minus p atmosphere even if epsilon is small because you do not know whether that uc is large or uc is small so you have the scales and these scales see the beauty or physics of these problems is that these scales are not so much describable a priority these scales depend on the physics of the problem so what is the dominating factor is it the body force is it the boundary condition along y direction is it the boundary condition along x direction or whatever is it the surface tension gradient like what will be uc for example if you have a surface tension gradient if you have a surface tension gradient then what will be uc the surface tension gradient then we will dictate what is uc how will you find out uc you have like the surface gradient of surface tension coefficient is equal to the tangential stress and the tangential stress scale is mu uc by h 0 so from there you will get the appropriate uc so depending on what is the dominating factor you will get the scale established from that parameter so when we describe the lubrication theory we do not say what is uc what is vc all these because these are apparently unknown generalized parameters which can only be affixed once you know what is the physical situation governing the problem so the important question is that exactly what we should solve for see there are too many equations there are quite a few boundary conditions so what we actually solve for so we saw in the lubrication theory one of the main unknowns is pressure here also pressure is an unknown along with that the film thickness is not known a priority once the pressure and the film thickness is known all other quantities can be easily deduced hence our aim should be to find out an equation for film thickness using the available equations and boundary conditions we will take it up in the next lecture thank you very much.


so here is another question guys the question says what does area under a velocity time graph give okay so whether does it give distance acceleration displacement or another so let's first find out what does it mean right so area under a velocity time graph again just to remind this is velocity time graph so in motion chapter you would have come across at least two varieties of such graphs one is position time graph displacement time graph or you know position time graph or displacement time graph or velocity time these are the things right so what does velocity time graph give okay so let us first draw the graph this is x and y coordinate axis so this x is nothing but our t so this is t and this is velocity t isn't it this is what our velocity time graph looks like and let us say the graph is something like this okay what are these values so here it is t is equal to t1 and at t equals to t1 the body was moving with velocity v1 and let me say this is t is equal to t2 okay this is t is equal to t2 and corresponding to this t2 the body had velocity v2 i'm writing it here so what does the area under the curve first of all understand what is area under the curve so if i have to just let me take another color for better understanding so if i take yeah so area under the curve is nothing but area bound between the given graph the time axis and the two perpendicular line corresponding to two time x two time values so between these two time okay this is what is area so we have to basically calculate this area we don't need to calculate we need to understand what exactly this means so for that what we're going to do is let us take let me take another color for how do we find out what exactly does it give okay so let me take this one now if you take any time t right any time t and corresponding to that time t let us say this is my v okay and let's take some some time after t but at a very small time gap okay so i'm saying this time gap is or this time is actually t plus delta t delta t small delta t is there so and then again draw a vertical line so you find out its corresponding velocity value let's say this value is v plus delta v now understand once again at time t the velocity was v okay no doubt at time t the velocity of the object is v which is given by this point so this is at this location at this time this is the velocity and at t plus delta t so this gap if you see if you this see this gap this gap is nothing but delta t gap so in a duration delta t so i'm writing delta t here so in delta t time gap the velocity increases by some value delta v right so hence this location now this point is v plus delta v okay now don't you think the this this particular diagram here so let's let me name it so let's say this point here is a this b this is c and this point is d so abcd looks like a trapezium abcd is a trapezium is a trapezium is it it now what is the rough cut area of roughly what is the rough area of this trapezium so if delta t is too small so this trapezium is almost like a rectangle right so this is anyways 90 degree this is anyways 90 degree so only this slant line is there but if delta t is too small you can say that this is almost like a rectangle so hence nearly this abcd has an area what ad into assuming it to be closer to the rectangle so ad into ab almost like a rectangle yes it's not exact but somewhat what is ad if you see ad ad is nothing but the v check this ad here is same as this v in this axis and what about this ab ab is nothing but delta t if you check isn't it so now it is as we are saying that for delta t amount of time the velocity was v and hence this particular quantity is nothing but distance traveled or displacement travel in this case velocity is given so displacement traveled in delta t time right at a velocity at a velocity how much v is it so hence this small area if i shared it using the screen so this area is displacement covered in delta t time so don't you think if i add all these small small trapeziums though you know if you somehow find out the exact trapezium area then don't you think this will give you the displacement cover between t1 and t2 so if in in abcd you can see in delta t time the displacement cover is given so from t equals to t1 to t equals to t2 if you add all such small small small trapezium areas you will get what displacement covered so hence area area under vt graph gives what gives displacement again remember it gives you displacement area under vt graph gives displacement if it is speed time graph it will give you distance simple so yeah so hence distance will be from speed time graph speed time right so hence right answer is c in this case but where do how do i get acceleration from vt so how do i get acceleration from vt graph so if you see if you have a vt graph so acceleration is nothing but the slope of the line okay so slope of this curve okay so let's say this is delta t and this is delta v what is delta v change of velocity from v1 to v2 okay and delta t is change of time from t1 to t2 so my dear friend this is delta t isn't it okay so hence acceleration a is given by delta v by delta t which is v2 minus v1 change in velocity divided by time taken to affect that change right in how much time that change was happening so hence this is acceleration so acceleration is nothing but how do i find out acceleration so what is it actually so what did we calculate if you remember the concept of slope so we calculated slope so slope of vt graph gives acceleration isn't it right so this is what is our learning so distance is given by area under speed time graph acceleration is given by slope of velocity time graph and displacement is given by area under velocity time graph i hope you understood this part