Dear Prem,

I have some related experience that may be helpful.

Once I worked on a project modeling a transient fluid in ANSYS for conditions such that flashing conditions were being achieved.

ANSYS does not have too elaborated thermodynamic packages, and it would be difficult to implement one, more so when it is a research subject that is being constantly developed.

But ANSYS gives you the values for the main variables you may need, such as temperature and pressure.

My solution was to simulate the thermodynamic behavior (static equilibrium) outside of ANSYS but within the range of variation of the “thermodynamic variables.”

Then I turned a simple empirical equation, easy to program in ANSYS, that may provide accurate information of all thermodynamic variables as a function of what ANSYS could best handle.

In my case, ANSYS gave us the right temperature and pressure along the pipe we were simulating. Then, I correlated the phase behavior model and let ANSYS know how density was changing, at what point (P and T) the flashing was taking place, the densities and mass ratios of the separating phases, etc.; this worked.

Static fluids are incompressible, so probably, this can be approached in an even more straightforward way.

I hope this helps.