RR in openFOAM

How RR is defined in OpenFOAM. We won’t dig into the code too much here. I come up with writing this when I read binary.C.

RR is defined in thermodynamicConstants.C as:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
 namespace Foam
 {
 namespace constant
 {
 namespace thermodynamic
 {
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
     // Note: the 1e3 converts from /mol to /kmol for consistency with the
     // SI choice of kg rather than g for mass.
     // This is not appropriate for USCS and will be changed to an entry in
     // the DimensionedConstants dictionary in etc/controlDict
     const scalar RR = 1e3*physicoChemical::R.value();
 
...
 
 } // End namespace thermodynamic
 } // End namespace constant
 } // End namespace Foam

R is defined in physicoChemicalConstants.H as:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
namespace Foam
{
namespace constant
{
namespace physicoChemical
{

...
    //- Universal gas constant: default SI units: [J/mol/K]
    extern const dimensionedScalar R;
...

} // End namespace physicoChemical
} // End namespace constant
} // End namespace Foam

If you want to use these two values, include constants.H and librarylibOpenFOAM when make the file. Test them use the following code:

1
2
Info << "RR is " << Foam::constant::thermodynamic::RR << nl;
Info << "R is " << Foam::constant::physicoChemical::R << nl;

Remember here RR is a dimensionless scalar and R is a dimensioned scalar.