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 total fuel mass
fraction 
, 
and unburnt fuel
mass fraction 
and 
and compressibility 
and compressibility 
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. The data is specified using a compound entry with the following format for a specie accessed through the keyword mixture:
mixture <specieCoeffs> <thermoCoeffs> <transportCoeffs>
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The thermodynamic coefficients <thermoCoeffs> 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 
following the <specieCoeffs>.
- eConstThermo
- assumes a constant
and a heat of fusion 
which is
simply specified by a two values 
following the <specieCoeffs>.
- 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 7.3. 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
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The transport coefficients <transportCoeffs> 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 values 
following the
<thermoCoeffs>.
- sutherlandTransport
- calculates
as a function of temperature 
from a
Sutherland coefficient 
and Sutherland temperature 
, specified by
values following the <thermoCoeffs>; 
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, with comments to explain the entries:
fuel // keyword
fuel 1 44.0962 // specie
200 5000 1000 // -- janafThermo --
7.53414 0.0188722 -6.27185e-06 9.14756e-10 -4.78381e-14
-16467.5 -17.8923
0.933554 0.0264246 6.10597e-06 -2.19775e-08 9.51493e-12
-13958.5 19.2017 // -----------------
1.67212e-06 170.672; // sutherlandTransport
mixture // keyword
air 1 28.9 // specie
1000 2.544e+06 // hConstThermo
1.8e-05 0.7; // constTransport