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
7.1.
Equation of State -- equationOfState
perfectGas
Perfect gas equation of state
Basic thermophysical properties -- thermo
hConstThermo
Constant specific heat model with evaluation of
enthalpy and entropy
janafThermo
evaluated by a function with coefficients from JANAF
thermodynamic tables, from which , are evaluated
Derived thermophysical properties -- specieThermo
specieThermo
Thermophysical properties of species, derived from ,
and/or
Transport properties -- transport
constTransport
Constant transport properties
sutherlandTransport
Sutherland’s formula for temperature-dependent transport
properties
Mixture properties -- mixture
pureMixture
General thermophysical model calculation for passive gas
mixtures
homogeneousMixture
Combustion mixture based on normalised fuel mass
fraction
inhomogeneousMixture
Combustion mixture based on and total fuel mass
fraction
veryInhomogeneousMixture
Combustion mixture based on , and unburnt fuel
mass fraction
dieselMixture
Combustion mixture based on and
multiComponentMixture
Combustion mixture based on multiple components [**]
chemkinMixture
Combustion mixture using CHEMKIN thermodynamics and
reaction schemes database files
Thermophysical model -- thermoModel
hThermo
General thermophysical model calculation based on
enthalpy
hMixtureThermo
Calculates enthalpy for combustion mixture
hhuMixtureThermo
Calculates enthalpy for unburnt gas and combustion
mixture
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:
The specie coefficients <specieCoeffs> contains the entries listed in 7.2 in the
order that they are specified in input.
Description
Entry
String name
e.g.mixture
Number of moles of this specie
Molecular weight
Table 7.2:
Specie coefficients.
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>.
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 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.
Description
Entry
Lower temperature limit
Upper temperature limit
Common temperature
High temperature coefficients
High temperature enthalpy offset
High temperature entropy offset
Low temperature coefficients
Low temperature enthalpy offset
Low temperature entropy offset
Table 7.3:
JANAF thermodynamics coefficients.
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)
The following is an example entry for a specie named fuel modelled using
sutherlandTransport and janafThermo, with comments to explain the entries:
system from which other
properties are computed. There is one compulsory dictionary entry called
model with evaluation of
enthalpy 
and entropy 
evaluated by a function with coefficients from 
, 
are evaluated 
, 
and/or 
and total fuel mass
fraction 
, 
and unburnt fuel
mass fraction 
and 
from which other properties are derived. The
current 
and a heat of fusion 
which is
simply specified by a two values 
following the 
as a function of temperature 
from a set of
coefficients taken from 
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:
and 
, both at high
and low temperature, used to evaluating 
and 
respectively.
, thermal conductivity 
and laminar thermal conductivity
(for enthalpy equation) 
. The current 
and Prandtl number 
which is simply specified by a two values 
following the
as a function of temperature 
from a
Sutherland coefficient 
and Sutherland temperature 
, specified by
values following the 
is calculated according
to:
