Hi all,

I trying to test 2d incompressible navier-stokes code, using plane poiseuille flow test case .

I am solving steady state system on a square domain. No-slip on top and bottom walls. Velocity inlet on the left where I specify Dirichlet parabolic profile ("x[1]*(1-x[1])", "0.0"). On the right boundary I specify zero constant pressure.

noslip = Constant((0, 0))

inlet = Function(P2).interpolate(Expression(("x[1]*(1-x[1])", "0.0")))

bc0 = DirichletBC(W.sub(0), inlet, 1)

bc1 = DirichletBC(W.sub(1), 0, 2) # zero pressure outlet

bc2 = DirichletBC(W.sub(0), noslip, 3)

bc3 = DirichletBC(W.sub(0), noslip, 4)

I expect the exact to be v = ( y (1 - y), 0) - (unidirectional flow).

However, I think I must have set that outlet condition up incorrectly as I get vertical flow near the outlet. Is this a common issue? or a sign that there's some bug in my formulation?

Thanks,

Fryderyk