Learning Forum

[Avedistchamitchian]

Dear Friends and Colleagues,

I am currently looking forward to applying Peng-Robinson Equation for the density model but I intend to customize its inner parameter like the Acentric Factor 'w'. and maybe other parameters too like alpha...

Going in the 'Create/Edit Material' tab after choosing Peng-Robinson for density,  under 'Acentric Factor' one can find 'constant' or 'New Input Parameter', and no 'User Defined' which means I can't just define a UDF Define_Properties in order to express my custom 'Acentric Factor' expression and hook it to the 'Acentric Factor' tab. 

Now I tried the 'New Input Parameter' option but as it seems I can only write a constant and not an expression.

For this, I would like to ask if there is a way to for example modify the 'Acentric Factor' or Peng-Robinson inner parameter expressions without really writing a full RGUDF for the Peng-Robinson model.

Gratefully yours

With kind regards  

[Rob]

Looking at the manual you may not be able to set the terms via DEFINE_PROFILE - have a look in the User's Guide and UDF Manuals for how the UDRGM are set up.

[Avedistchamitchian]

There is a solution that is setting it up in the same way UDRGM is done.
But I would prefer to work with Define_propertiesor other Define_... Macro if it works? for the reason, that I don'tneed to re-define all Physical properties (density, enthalpy, entropy,specific_heat,......) but only specific ones.
Let me rephrase, the problem in UDRGM is I need to set up all the equations the way fluent does in the background for all the Physical properties, for example, if I want to use kinetic-theory for Cp or Viscosity I need to know the right equation and write it in my UDRGM since after loading my UDRGM code I cant select all the Physical properties anymore.