Couette Flow

1. The driving force is the shear stress between the moving wall and the fluid. Shear stress is constant across the flow for both incompressible and compressible cases.

2. For incompressible Couette flow,

[16.6]

[16.9]

3. The heat transfer depends on the wall temperatures and the amount of viscous dissipation. For an adiabatic wall, the wall enthalpy is

haw = he + r1^- [16.46a]

For incompressible and compressible Couette flow with a constant Prandtl num­ber, the recovery factor is

r = Pr

and Reynolds analogy holds in both cases;

— = – РГ1 [16.59]

cf 2

16.6.2 Poiseuille Flow

1. The driving force is a pressure gradient in the flow direction, generated by some outside mechanism. This fully developed flow is a force balance between the pressure gradient and shear stress at the walls.

2. For incompressible flow, the velocity profile is parabolic, and is given by