Information on radiation modeling in multiple domains is available. For details, see Domain Considerations.
To determine the direction of the rays, the unitary hemisphere over the face of a parametric element is discretized using spherical coordinates. The span is divided into angles by the number of rays, and rays directions are computed to pass through the center of the angles. In total, the square of the number of rays is traced from an element surface. The default is set to 8.
The Transfer Mode setting defines which radiative
transfer mode is enabled. The default value is Participating
Media; that is, the domain material emits, absorbs, and/or
scatters radiation. The Surface to Surface option implies
that volumetric emission, absorption and scattering are ignored regardless of
the specified material properties.
Note: Solution time may be adversely affected when using the Surface to Surface option in a case involving a subdomain that
only partially covers the whole domain. With the Surface to Surface option, the CFX-Solver
tries to reduce the radiation mesh to a single element (because only surfaces are of interest) but the presence of the subdomain
causes the number of elements to be at least two, triggering a potentially time-consuming ray trace.
This problem applies to both the Discrete Transfer and Monte Carlo models.
The workaround is to use the Participating Media option instead of the
Surface to Surface option and adjust the coarsening controls to produce a coarser radiation
mesh than the default. Choosing a coarsening rate that produces a few hundred radiation elements should
result in a solution similar to that under the Surface to Surface option,
but with perhaps not the same resolution of the intensity field at the boundaries.
See Spectral Model.
See Scattering Model.