Hi, I am running an airfoil simulation for NACA 0012 in the cfd code FLUENT. I am using the pressure far field type of boundary condition where the mesh is of the "C" type. When I ran for high MACH number, the simulation goes on smoothly but when i used MACH number 0.04, my solutions diverge till 10e+8. Can anybody tell me how i can remedy this?

Rif

What diverges to 10e+8... continuity?, energy?, turbulence?

Energy...

I would suggest starting the solution more gradually, to ramp up on the final flow field. Also, consider reducing the under-ralaxation values for continuity, turbulence and energy in the early iterations of the flow field, until the overall flow field is well established. Then, increase the under-relaxation variables back to normal levels. I think your solution will be stable then. Remember, the actual airfoil did not reach this state instantaneously in the rig test, so the CFD solution solver should not be expected to either!

Hope this helps.... Happy Computing!