Participating Media Radiation (Spherical Harmonics) Reference

The Spherical Harmonics model uses spherical harmonics to describe the directional component of radiation intensity in media that can absorb, emit, or scatter thermal radiation .

The Participating Media Radiation (Spherical Harmonics) model is faster than the Participating Media Radiation (DOM) model but applies to a more limited range of scattering and boundary conditions. This model does not simulate refraction or specular reflection. It is lower in accuracy than the DOM model at boundaries and for situations with large directional gradients of intensity. It is not compatible with other radiation models or with overset mesh.


Theory	See Participating Media Spherical Harmonics.
Provided By	[physics continuum] > Models > Radiation
Example Node Path	Continua > Physics 1 > Models > Participating Media Radiation (Spherical Harmonics)
Requires	Space: Any Optional Models: Radiation
Properties	Key properties are: Secondary Gradients. See Participating Media (Spherical Harmonics) Properties.
Activates	Boundary Inputs	See Participating Media (Spherical Harmonics) Boundary Settings.
	Solvers	Spherical Harmonics Radiation. See Spherical Harmonics Radiation Solver Properties.
	Monitors	P1
	Field Functions	Boundary Irradiation, Boundary Radiation Heat Flux, Boundary Radiosity, Incident Radiation, Radiative Absorbtion, Radiative Energy Source, Total Absorption Coefficient, Total Emissivity. See Radiation Field Function Reference.

Participating Media Radiation (Spherical Harmonics) Properties

Secondary Gradients

Neglects or includes the boundary secondary gradients for radiation or the interior secondary gradients at mesh faces.

On: Includes both secondary gradients.
Off: Excludes both secondary gradients.
Interior Only: Includes the interior secondary gradients only.
Boundaries Only: Includes the boundary secondary gradients only.

Boundary Settings

Inflow Boundaries, Pressure Outlet, Free Stream , Wall

Radiation Flux Option

This option allows you to model diffuse radiation sources at boundaries according to your own specification. See Diffuse Radiation Flux.

Radiation Flux Option	Corresponding Physics Value Nodes
No flux	None
Diffuse radiation flux	Diffuse Radiation Flux The diffuse radiation flux is specified as a scalar profile. Requires the Multiband Thermal Radiation or Gray Thermal Radiation model.

Inflow Boundaries, Pressure Outlet, Free Stream

Radiation Temperature: The temperature of an open boundary that has a total radiant emittance identical to that of a black body. See Radiation Temperature.

Spherical Harmonics Radiation Solver Properties

Solver Frozen: When On, the solver does not update any quantity during an iteration. It is Off by default. This is a debugging option that can result in non-recoverable errors and wrong solutions due to missing storage. See Finite Volume Solvers Reference for details.
Solver Order Option: Sets the order of Legendre polynomial used for the spherical harmonics calculation Eqn. (1752). At present, the only value available is P1.