7.1 Thermophysical models
Thermophysical models are concerned with the energy, heat and physical properties.
The thermophysicalProperties dictionary is read by any solver that uses the
thermophysical model library. A thermophysical model is constructed in
OpenFOAM as a pressure-temperature 
system from which other
properties are computed. There is one compulsory dictionary entry called
thermoType which specifies the complete thermophysical model that is
used in the simulation. The thermophysical modelling starts with a layer
that defines the basic equation of state and then adds more layers of
modelling that derive properties from the previous layer(s). The naming of
the thermoType reflects these multiple layers of modelling as listed in
Table 7.1.
model with evaluation of
internal energy 
and entropy 
model with evaluation of
enthalpy 
and entropy 
evaluated by a function with coefficients from
polynomials, from which 
, 
are evaluated 
evaluated by a function with coefficients from 
, 
are evaluated 
, 
and/or 
, 
and unburnt fuel
mass fraction 
and 
and compressibility 
and compressibility 
and compressibility 
and 
and 
and 
and 
The thermoType entry typically takes the form:
thermoModel<mixture<transport<specieThermo<thermo<equationOfState>>>>>
hThermo<pureMixture<constTransport<specieThermo<hConstThermo<perfectGas>>>>>
7.1.1 Thermophysical property data
The basic thermophysical properties are specified for each species from input data. Data entries must contain the name of the specie as the keyword, e.g. O2, H2O, mixture, followed by sub-dictionaries of coefficients, including:
- specie
- containing i.e. number of moles, nMoles, of the specie, and molecular weight, molWeight in units of g/mol;
- thermodynamics
- containing coefficients for the chosen thermodynamic model (see below);
- transport
- containing coefficients for the chosen tranpsort model (see below).
The thermodynamic coefficients are ostensibly concerned with evaluating the
specific heat 
from which other properties are derived. The current thermo
models are described as follows:
- hConstThermo
- assumes a constant and a heat of fusion
which is
simply specified by a two values 
, given by keywords Cp and Hf.
- eConstThermo
- assumes a constant
and a heat of fusion 
which is
simply specified by a two values 
, given by keywords Cv and Hf.
- janafThermo
- calculates
as a function of temperature 
from a set of
coefficients taken from JANAF tables of thermodynamics. The ordered list of
coefficients is given in Table 7.2. The function is valid between a lower and
upper limit in temperature 
and 
respectively. Two sets of
coefficients are specified, the first set for temperatures above a common
temperature 
(and below 
, the second for temperatures below
(and above 
). The function relating 
to temperature
is:
(7.1) In addition, there are constants of integration,
and 
, both at high
and low temperature, used to evaluating 
and 
respectively.
- hPolynomialThermo
- calculates
as a function of temperature by a polynomial
of any order. The following case provides an example of its use:
$FOAM_TUTORIALS/lagrangian/porousExplicitSourceReactingParcelFoam/filter
The transport coefficients are used to to evaluate dynamic viscosity 
,
thermal conductivity 
and laminar thermal conductivity (for enthalpy
equation) 
. The current transport models are described as follows:
- constTransport
- assumes a constant
and Prandtl number 
which is simply specified by a two keywords, mu and Pr, respectively.
- sutherlandTransport
- calculates
as a function of temperature 
from a
Sutherland coefficient 
and Sutherland temperature 
, specified by
keywords As and Ts; 
is calculated according to:
(7.2) - polynomialTransport
- calculates
and 
as a function of temperature 
from a
polynomial of any order.
The following is an example entry for a specie named fuel modelled using sutherlandTransport and janafThermo:
fuel
{
specie
{
nMoles 1;
molWeight 16.0428;
}
thermodynamics
{
Tlow 200;
Thigh 6000;
Tcommon 1000;
highCpCoeffs (1.63543 0.0100844 -3.36924e-06 5.34973e-10
-3.15528e-14 -10005.6 9.9937);
lowCpCoeffs (5.14988 -0.013671 4.91801e-05 -4.84744e-08
1.66694e-11 -10246.6 -4.64132);
}
transport
{
As 1.67212e-06;
Ts 170.672;
}
}
air
{
specie
{
nMoles 1;
molWeight 28.96;
}
thermodynamics
{
Cp 1004.5;
Hf 2.544e+06;
}
transport
{
mu 1.8e-05;
Pr 0.7;
}
}
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