I want to analyse supersonic flow (air) over rectangular cavity located at the bottom wall of rectangular duct using NISA-3D FLUID(COMPRESSIBLE) Package.

Since the pressure inside is oscillatory, I need to evaluate Pressure at selected nodal points at every 10 micro second for 25000 times continuously so that this can be used to find frequencies of pressure oscillation using FFT.

How to determine pressure values as above in NISA package.

If not possible, any other package available?

my friend,

first you learn what is FEM, then go for unsteady pressure picking . I mean you must be thorough in basics. It seems that you want to do unsteady FEM using NISA in a short time. It will be impossible for people like you . OK all the best.