Hi friends, I face problems in simulating a supersonic diffuser flow. I use a UNS FVM solver. The inlet mach no. is 3.5 and no condition is specified in the down stream side(pressure extrapolated). The diffuser is supposed to be of proper dimensions with a straight long throat. Still the flow has not become subsonic or no shock is formed. The exit pressure is above the expected value. My doubts are:i) Should I specify the subsonic conditions at the down stream side? ii) How can I implement that? iii) If I specify the exit pressure will it simulate the real situation? Could any one give some help?? Thanks.. Dileep.

Hi Dileep,

You can implement a boundary condition which can check every iteration whether the live cell Mach no at the exit is subsonic and supersonic. It should apply pressure for subsonic case else go for extrapolation.

Note : Not the expert's comments ... any other suggestions... please enlighten me also.

Regards,

Jitendra