Setting relaxationsfactors

Phil

I try to investigate a flow (water) between two corrugated plates (isotherm), mass flow inlet, pressure outlet and I found out that my solution converges only when my relaxationfactor for momentum is very small (=0.01). I'm using Simplec algorithm for the pressure velocity coupling. It's a steady-state 3d simulation and I use the segregated implizit solver. The flow is laminar. I tried to solve it with values which are closer to the default values in Fluent, but then I don't reach convergence.The change of the underrelaxationsfactors of the pressure has no influence, so I set them as default values.

Any ideas

Phil