Hi everyone, I am doing supersonic flow study in a combustor.I want to know how important is the effect of Courant number on the solution ,convergence etc. I am presently using Courant number of 0.5. How far can I change it from my present value to get better results.

Regards sridhar

A CN of less than 1 is always satisfactory for an implicit solver. Practically a RMS CN <= 1 and MAX CN <= 5-10 is usually satisfactory for adaquate accuracy for an implicit solver. You can go bigger but you must then show solution insensitivity to a CN > 1.

thanks for the rply .. just help me out with another small doubt of mine ..mine is an injection problem and the main flow is supersonic with sonic injection .I would like to know . should I start with UNSTEADY solution or start with STEDY SOLN and then switch to unsteady solution.. Please suggest ..thanks

Start with a steady solution and then do the unsteady soultion.