1. how do u specify whether the simulation is compressible or incompressible in star-CD?? any option? or any function of density??

2.how can one see moving mesh problem as to whether it is running properly or not without worrying abt the thermophysical models. is there any special button? and how can one do the post processing so see diffeerent positions of a moving body wrt a stationary body.

Usually it helps very much to read the manual and work through the tutorials.

Q2) rcon,4,1

In the STAR GUIDE Thermophysical Models and Properties\Liquids and Gasses\Molecular Properties

for Density Tab select Ideal-f(T,P) this make the density a function of temperature and pressure, which is incompressible flow. A constant density is used for incompressible flow. Check your Mach numbers to see if you actually need compressiblity (Ma<0.3 incompressible)

For moving mesh u read the tut-13 of star-cd and then try to see how it moves.Basically u have to execute some coding thru a loop facility of star-cd.