Unstructured Ahmed Body LES
 

For my Masters Thesis I am attempting to run Large Eddy Simulation on an unstructured bluff body mesh to see the effect on drag and flow control. However, the solution will diverge almost instantly. While it might be my setup in FLUENT, I was hoping to get some guidelines for what kinds of things I should look out for in the meshing process. Currently, I am running 10 prism layers at y+ of 1 and growth factor of 1.2. There are a few higher refinement boxes around the body and the majority of the field is quite coarse. Should I use Hexa-dominant or Tetra in ICEM? Any other hints that could improve my mesh?