I was trying to reproduce the simple Couette flow with COMSOL but I am having troubles with it.

I select the Incompressible Navier Stokes option from the Chemical Engineering package, then I draw a rectangle of length 2 in the x direction and 0.4 in y.

The inlet is the vertical edge on the left and the outflow is the vertical edge on the right. The lower horizontal edge should be steay, while te upper one should move in the positive x direction.

The boundary conditions are:

Inlet: Inflow/Outflow velocity u0=2e-2*y v0=0 Outlet: Normal flow/pressure p=0 Lower edge= no slip

The problem is defining the boundary condition of the upper edge. If I use Slip/Symmetry or Neutral, the gradient of the velocity in the direction perpendicular to the upper edge is automatially set to zero, so the profile becomes more and more parabolic for an increasing viscosity.

The only way to express the x velocity is to select Inflow/Outflow velocity and put u0=2e-2*0.4 v0=0. If I do so, the solver crashes.

Is there any stupid error that I am not noticing or there is an option which I am not aware of?

[baranii2000]

Hi Marco,

Did you find the solution for Couette flow in Comsol? i am facing the same problem. Can you tell me how you get it sorted?