Fatal over flow in solver

Nandu

Hi,

I'm modelling supersonic jet flows into still air. I have managed to get convergence of M = 1.41 (ideally expanded) flow into still air using a local timestep factor for the solver control in CFX 5.5

When i change the inlet pressure conditions in the results file from the previous simulation so that i can get an underexpanded or over expanded jet, the solver crashes with the error being a 'fatal over flow in the liner solver'.

This error also comes when i use a new definition file with the old results file as an intial guess. Changing the local time step factor has not helped. The failure of the simulation is the at the 1st timestep. Any help to rectify this situation is most appreciated.

regards N Menon