Converge issue on steady state pump
 

I have a mesh of a pump that has Boundary layers on the parts : blade, hub, shroud. it has periodic walls and inlet/outlet.

The BL mesh has elements with aspect ratio of 20000 and a number of jacobian with 0.42 the smaller.

I try to run this pump on CFX and the solver can not converge at the timestep of 1/ω, I am using SST as turbolence model.

If i apply timestep at 1e-9 the solver converge but the results are really bad.

Do you think that might be the mesh that creates the issue? or i have to check something else?

An aspect ratio of 20000 is pretty bad, even in a boundary layer mesh. I agree with you, I suspect you have inadequate mesh quality.