I am trying to the see the effects of a diffuser with an axial (u) plug inlet profile and rankine vortex velocity profile specified at the inletl. The grid has been generated and as far as i know is ok. The problem i am facing is that though i have specified the tangential velocity (w) profile, i am unsure how to tie it to the axial velocity (u). Basically, i am trying to write subroutines in fortran than defines the axial velocity profile from the tangential.

Dear Olu

I am not sure if I understand your problem, but you can very easy in usrbcs.f define the axial velocity from your tangential velocity, I even think there are some standard examples on using usrbcs.

Regards Jan