If the Radiation discretization method is
P1 approximation, the incident radiation
G is the solution of the following equation
where DP1 is the P1 diffusion coefficient.
When Wavelength dependence of radiative properties is
Solar and ambient or
Multiple spectral bands in the
Participating Media Settings section of the interface,
Equation 6-1 and
Equation 6-2 are solved for each spectral band
k:
Ii,k is the
ith component of the radiative intensity for spectral band
k, and
Gk is the incident radiation for spectral band
k.
If radiative emission should be considered as well, the Participating Medium (Radiation in Participating Medium Interface) node should be used instead. The table below describes the different effects accounted for by the interfaces found under the
Heat Transfer>Radiation branch (
).
This section is available when temperature-dependent material properties are used. The default Temperature is
User defined. When additional physics interfaces are added to the model, the temperature variables defined by these physics interfaces can also be selected from the list. The
Common model input option corresponds to the
minput.T variable, set to 293.15 K by default) and all temperature variables from the physics interfaces included in the model. To edit the
minput.T variable, click the
Go to Source button (
), and in the
Default model Inputs node under
Global Definitions, set a value for the
Temperature in the
Expression for remaining selection section.
The Absorption coefficient κ should be specified. It defines the amount of radiation,
κI(Ω), that is absorbed by the medium.
The Absorption coefficient κ (SI unit: 1/m) uses values
From material by default.
For User defined, set a value or expression. You may set a temperature-dependent absorption coefficient through the use of the variable
rasm.T.
If Wavelength dependence of radiative properties is
Solar and ambient or
Multiple spectral bands, the wavelength may be accessed through the
rasm.lambda variable. Any expression set for the absorption coefficient is then averaged on each spectral band to obtain a piecewise constant absorption coefficient. If the average value of the absorption coefficient on each band is known, you may use instead the
User defined for each band option to avoid the evaluation of the average.
When Absorption coefficient is set to
User defined for each band, enter a value for the
Absorption coefficient for each spectral band in the table displayed underneath. Within a spectral band, each value is supposed to be wavelength-independent.
The Scattering coefficient σs (SI unit: 1/m) uses values
From material by default.
For User defined, set a value or expression. You may set a temperature-dependent scattering coefficient through the use of the variable
rasm.T.
If Wavelength dependence of radiative properties is
Solar and ambient or
Multiple spectral bands, the wavelength may be accessed through the
rasm.lambda variable. Any expression set for the scattering coefficient is then averaged on each spectral band to obtain a piecewise constant scattering coefficient. If the average value of the scattering coefficient on each band is known, you may use instead the
User defined for each band option to avoid the evaluation of the average.
When Scattering coefficient is set to
User defined for each band, enter a value for the
Scattering coefficient for each spectral band in the table displayed underneath. Within a spectral band, each value is supposed to be wavelength-independent.
where is the anisotropy parameter and K is defined as follows to produce a normalized phase function:
For Linear anisotropic and
Polynomial anisotropic, select the
Normalize phase function check box to define a phase function such as
For Linear anisotropic,
Polynomial anisotropic, and
Henyey-Greenstein, select the
Wavelength-dependent scattering type check box to average each
Legendre coefficient a1, …,
a12 or the
Anisotropy parameter μ to obtain piecewise constant coefficients on each spectral band.