[koala]

Hey,

I'm trying to create a simple test case for further implementation validations. I'm using a multi physics solver but the fluid dynamics solver is the same as pisoFoam. So my testcase is a simple channel (100mm x 0.3 mm x 0.5mm) and the mesh is 2000 x 15 x 9 cells. I tried two different boundary conditions:

Inlet:
U: fixedValue (1 0 0)
p: zeroGradient

Outlet:
U: zeroGradient
p: fixedValue 0

Walls:
U: fixedValue (0 0 0) OR slip
p: zeroGradient OR slip

In the case with fixedValue for U and zeroGradient for p at the Walls, I get a perfect converged result. But for the case with slip conditions, theres almost no convergence. Is there a explanation for this behavior?

I attached my fvSolution, fvSchemes and the two residual plots.