[harshavardhanps3839]

"I am trying to model incompressible flow in a diffuser. I take advantage of the symmetry boundary condition and model only one-quarter of the diffuser. The mesh on the walls are resolved finely to get y+~1. I give mass flow rate as an outlet boundary condition and atmospheric pressure as an inlet boundary condition. When I run this steady-state simulation, with the SST k-omega model, I get a surprise. The solution (continuity and u,v,w, momentum) residuals converge to 10^(-5) only and then start oscillating. The bigger surprise is that the wall shear stress does not go to zero (though it shows a decrease) at any point along the length of the diffuser. Kindly help, I do not know where I am making a mistake.

Your help is much appreciated.