[FluentStarter]

Dear Foamers,

I have some questions about the definition of fluid properties in OpenFOAM.

Initially I followed the tutorial by Huang (http://www.tfd.chalmers.se/~hani/kur...roject1211.pdf) to create a new fluid (in my case NH3). I tested the compilation initially without changing the values and everything went fine.
Now I'm working on introducing the actual fluid properties of NH3 into the solver. Those values are mentioned for gasoline in the tutorial, but there source is not?

The first parameters (molecular weight, critical temperature, etc. are easy to find in literature). However, I'm wondering what the standard practice for the coefficents of the NSRDS functions is.

I have several open questions and, based on several open threads that have not been answered yet, those questions should also be of interest on others working on two phase flows in OF:

1.) For example, when I go through the definition of the NSRDS functions, none of them is a function of the pressure, but only the temperature?If I consider the heat capacity and plot the values of the heat capacity based on the REFPROP database for NH3, those values do not only depend on the temperature, but also heavily on the pressure.
It seems like the current implementation does not include the dependency on the pressure or how are people handling this? Do I take the mean value?
I guess it would in theory be possible to rewrite the NSRDS functions and make them depended on pressure, but I was just wondering if there is really a reason for it? Maybe it is appropriate to neglect the pressure dependence?


2.) Which database are you using? Is REFPROP the right source for this? Can we get all of the needed values from there?

3.) In case I find a good curve for a certain quantity, then I just run a fitting procedure with the NSRDS function I would like to use to represent it to find out the coefficients?

4.) What is the idealGasHEat capacity? Isn't the definition that the heat capacity of an ideal gas is constant?


Any help would be highly appreciated.

[yang52079@outlook.com]

Is it a matter of writing your own files? You can upload the NH3 files to me for a look.