ideal or non-ideal equation of state
 

hello
I'm trying to use an equation of state (EOS) for a real gas with density based method for an inviscid compressible flow in a con-div nozzle.

firstly I tried to use a simple revision of real gas EOS (P = Ro*R*T) and wrote a UDF with define_property macro hooked to density in material panel.
when i run the UDF, the contour of static and total pressure will be the same.
it should be noted there is an other define_property macro hooked to sound-velocity but it has no influence on the solving procedure. because if the sound-velocity is set constant there is no differende between the solutions.

I think if we want to use a non-ideal EOS it is not sufficient to write a UDF just manipulate the density in material panel.
can any body help me