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Accessing thermoPhysical Property Functions - e.g. mixture_.rho(scalar p, scalar T)

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Old   June 23, 2015, 00:32
Default Accessing thermoPhysical Property Functions - e.g. mixture_.rho(scalar p, scalar T)
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Will Logie
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I am looking to post-process buoyantPimpleFoam (perfectGas rho, Sutherland mu, JANAF Cp) results and extract some heat transfer characteristics for a wall [patchi] based on the Rayleigh Number:

Code:
     Ra.boundaryField()[patchi]
  = (
        gravity * betaFilm.value()
      / (
            muFilm.value() 
          / rhoFilm.value()
          * alphaFilm.value()
        )
    )
  * (T.boundaryField()[patchi] - T_ref.value()) * pow(L.value(), 3);
The scalar values betaFilm, muFilm, rhoFilm and alphaFilm should be calculated from the film temperature (T_wall + T_ref) / 2 and L is the characteristic length loaded from a dictionary file.

Has anyone done this before or can give me some tips; for example, how best to access the member function:

Code:
template<class Specie>
inline Foam::scalar Foam::perfectGas<Specie>::rho(scalar p, scalar T) const
{
    return p/(this->R()*T);
}
from within a solver or post-processor (i.e. without going via the heRhoThermo class)?

My awareness of C++ is insufficient.

Thank you,
Will.
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Old   June 23, 2015, 05:35
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You need to get access to the thermo object which is used in the solver.
In the solver this is very simple, it's usually stored in a variable called thermo or something similar. Read your solver code for this.

In a different program you need to instantiate it the same way as it's done in the solver first.
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Old   June 23, 2015, 23:38
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Will Logie
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I'm aware that I can access any [celli] within the simulated thermo variable field which in turn is calculated from the pressure and temperature of that particular cell.

But what I am asking is how does one "calculate" one's own viscosity or density given some "reference" or desired pressure and temperature?

For example if I know my film temperature to be 467K at atmospheric pressure, I could calculated film values for density, viscosity and specific heat by way of the respective member functions - I imagine to look like rhoFilm = perfectGas.rho(1e5, 467)

Are you implying I could use thermo.rho() in this way, and if so how?
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