Divergence in Velocity Field
 

Hi,
I am trying to run a case with a udf (to include a source term in the Ergun Equation) and the velocity field diverges because the Global Courant Number increased beyond 250. I then switched over to variable time stepping option and decreased the time step size to 1e-8 and it still diverges. Can someone please advice on how to resolve this problem?

Thank you.
Vidya Raja