Kundu and Cohen:
Briefly explain what pressure is in terms of molecular motion. If we put a surface in the fluid what effect does the pressure have on the surface? Why doesn’t pressure have a direction?
In classical mechanics we usually describe forces acting on a particle. Why is this so hard in fluid mechanics, and why do we discuss things in the Eulerian frame?
If a fluid is incompressible, why must the sum of the linear strain rates be zero? i.e. if you squish a balloon in the x direction (convergence), what happens to the velocities in the y and z directions?
In the hydraulics demo, the water got thin over the weir. If the flow is steady, what does conservation of mass tell us about the flow speed at the top of the weir relative to upstream?