When the curl of the field representing this quantity is zero, a fluid is called irrotational; that curl is called
 the voriticity.
In two-dimensional Poseuille flow, the field describing this quantity takes on a parabolic profile. For a
 Newtonian fluid, the shear stress is given by the dynamic viscosity times the gradient in this quantity.
 When the curl of the field representing this quantity is zero, a fluid is called irrotational; that curl is called
 the voriticity. The no-slip condition defines where this quantity is zero, and the product of this quantity
 with the characteristic length and the density, divided by viscosity, yields the Reynolds number. In
 Bernoulli's equation, the square of this quantity balances the pressure integral. For 10 points, identify this
 quantity which according to Bernoulli's equation, causes a pressure drop in a fluid when it increases, and
 whose square times the mass gives the kinetic energy of a fluid flow.
In two-dimensional Poseuille flow, the field describing this quantity takes on a parabolic profile.
fluid {velocity}