Respected Sir i have the problem of Max scratch space while creating the mesh as per geometry, as the number of vertices increases then this problem occures memory cannot be allocated for MSCR2 above the limit set in Star-CD. How to change or increase that max limit of scratch space?

Your best bet is to run prosize before running prostar and tell it how big you need different numbers. Make everything a little bigger than what you think you need. You can also resize on the fly using the MEMORY command but you can't do that too many times before running out of virtual memory. If you are running on a 32bit machine and you need more memory than it can accomodate, you are out of luck.

Respected Sir Problem discription: i have to simulate a haloow U- tube , both ends are provided with Pressure boundary by user subroutine, the pressure at one end is "high" while at other end it is "low", the situation get reverse after some time step. this is mean that the flow get reverse (Oscillating type)at every time?