Hello everbody,

I have an issue with the convergence bahvior of the simulation of a flow around a ground vehicle using CFX 10.0 and an SBF=1. I am applying RANS and the SST-Model.

The wake of my vehicle is dominated by two vortices in the streamwise direction (created by the oblique flow over a rim on each side) and one vortex with its axis perpendicular to the free stream direction.

Using an SBF of 0.75 I always get good convergence behavior - however the accuracy of my C_D is not very good. SBF=1 provides much better accuarcy, however for some cases (essentially I am changing the angle of the base) I cannot get a converged solution (RMS=1e-4). The mesher (ICEMCFD) shows no problems or errors in the mesh and the quality is alright, too.

Has anyone of you met the same issues and can tell me what the reason might be? Additionally I would be very thankful to get some hints where in the literatur these issues of convergence beahvior are properly treated and explained. Is there any good textbook or series of papers on that?

thanks a lot Fonzie

Google: turbulence modelling ahmed body separation