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These guidelines are based on the working folder located here.

Thermophysical modelling

1) Species thermophysical properties

The species thermophysical properties are given in the thermoDEM dictionary. Each species presents three subdictionaries: specie, thermodynamics, and transport. An example is provided below for the nitrogen molecule,

N2
{
    specie
    {
        molWeight       28.0134;
        particleType    2;
        charge          0;
        diameter        4.17e-10;
        dissocEnergy    3.36e7;
        iHat            2.89e7;
        omega           0.74;
        eta_s           1.2;
        noVibTemp       1;
        noElecLevels    15; 
    }
    thermodynamics
    {
        decoupledCvCoeffs    ( 1.5 1 1 0 0 0 0 );
        vibrationalList      ( 1  3371 );
        electronicList       (  
                                1  0
                                3  7.223157e4
                                6  8.577863e4
                                6  8.605027e4
                                3  9.535119e4
                                1  9.805636e4
                                2  9.968268e4
                                2  1.048976e5
                                5  1.116490e5
                                1  1.225836e5
                                6  1.248857e5
                                6  1.282476e5
                                10 1.338061e5
                                6  1.404296e5
                                6  1.504959e5
                             );               
    }
    transport
    {}
}

where the entries of the transport subdictionary are omitted as they will be discussed in B. TRANSPORT. The following Table is listing the different keys present in the specie subdictionary and their meanings.

In the thermodynamics subdictionary, the first entry is a list of coefficients called decoupledCvCoeffs(). The heat capacity at constant volume, Cv, is decomposed into the contributions of the different energy modes that are translational (1st element), rotational (2nd element), vibrational (3rd element), electronic (4th element), and electron (5th element). For a planar molecule,

`Cv_t = \frac{ζ_t}{2} \times R_m = 1.5 \times R_m`

and

`Cv_r = \frac{ζ_r}{2} \times R_m = 1.0 \times R_m`

where `R_m` is the specific gas constant of molecule `m`. Thus, the first two elements in the decoupledCvCoeffs() list are the coefficients by which `R_m` should be multiplied.

For the vibrational and electronic modes, the expressions of `Cv_v` and `Cv_{el}` are a function of the values provided in the vibrationalList() and electronicList() lists. Hence, the 3rd and 4th elements can be regarded as switches (see §2.1 and §2.2). The elements in these two lists are grouped by pairs with the first column being the degeneracy and the second column being the characteristic vibrational/electronic temperature, in Kelvins.

The 6th element of the decoupledCvCoeffs() list is the ratio of the species chemical enthalpy taken at 298 K (in J/mol) to the universal gas constant, while the 7th element is currently not used.

2) Adding/removing energy modes

2.1 Disabling/enabling the vibrational mode of a molecule

In the thermoDEM/#speciesName/thermodynamics dictionary, edit the 3rd element of the decoupledCvCoeffs list to either be 0 (disabled) or 1 (enabled).

In the following example, the vibrational energy mode of the N2 molecule is accounted for

        decoupledCvCoeffs    ( 1.5 1 1 0 0 0 0 );

2.2 Disabling/enabling the electronic mode of a particle

In the thermoDEM/#speciesName/thermodynamics dictionary, edit the 4th element of the decoupledCvCoeffs() list to either be 0 (disabled) or 1 (enabled).

In the following example, the electronic energy mode of the N atom is accounted for

        decoupledCvCoeffs    ( 1.5 0 0 1 0 56852 0 );

3) Choosing a thermoDEM dictionary

Three thermoDEM dictionaries are provided in the generic hy2Foam test case. To account for

• the rotational energy mode only, choose thermoDEM_TR;
• the rotational and vibrational internal energy modes, choose thermoDEM_TRV;
• all internal energy modes, choose thermoDEM_TRVE.

NB: All species can be left uncommented at all times.