Hi everyone, I facing some problems in solving a supersonic flow arround a fin stabilized missile. The iterations seems to be stable using 2nd order schemes and spallart-allmars turbulent model. sudenly, after many iterations an error occured and a message of divergant detected appeared and the iterations stops. can any one tell me why?

You need to investigate the diverged solution. There was a message in the Fluent window which said which variable diverged (typically it's temperature) so you need to find where the problem is in your model. Look at the contours, make surfaces... things like that to find exactly where the problem is and try to convince yourself what's causing the problem. You should also look at the general flow field to make sure it makes sense... are shocks from your body interacting with BCs (if so, your domain is too small)... do the shocks look right and is the property change across them about right (if not, check your BCs and your material properties). Look for anything in the flow field that doesn't seem right. It could just be a localized mesh problem, or it could be something wrong with your setup. It's best to investigate as much as you can now rather than spending a lot of time re-meshing and realizing it was a setup problem.

Hope this helps, and good luck, Jason