I'm using CFX TASCflow to model the 2d jet structure at the exit of a supersonic nozzle. Im having convergence problems using a supersonic inlet condition and a supersonic outlet condition to my flow domain. If any one has any prior experiance in a problem of this nature, your sugegstions will be most welcome

If your nozzle is exiting in a small chamber, use a pressure boundary at the exit of this chamber (enviromental pressure). The flow should come to a halt via a number of shocks. I'm not sure about your supersonic inlet. Is that the end of the nozzle (ie your not modelling the flow in the nozzle itself? I'm using CFX 5. For these flows we can use physical timestepping with timesteps typically 1e-4 s. The starting up of the flow may require smaller steps and a first order schema. If this is of no help, you can contact me via email.