Volumetric Radiation Exchange Workflow

Simcenter STAR-CCM+ provides three models for simulating exchange of radiant energy in volumes:

Discrete Ordinate Method (DOM)—solves for radiation intensity along specified directions, with each direction representing a discrete solid angle.
Spherical Harmonics model—describes directional flow of radiation in terms of spherical harmonic functions.
Volumetric Photon Monte Carlo (VPMC) model—provides a higher-fidelity alternative to the existing PDE-based, deterministic radiation models (DOM and Spherical Harmonics). This model also allows for combined volumetric/surface radiation modeling wherein some of the regions are participating while the other regions have surface-to-surface radiation enabled; radiative energy can seamlessly travel between these regions.

All these models simulate thermal radiation exchange between diffuse/specular surfaces forming a closed set. The medium that fills the space between the surfaces can also absorb, emit, or scatter radiation. The amount of radiation that each surface receives and emits depends on this effect, as well as the optical properties of the surface and the thermal boundary conditions that are imposed on it.

To model volumetric radiation exchange:

For the physics continuum Continua > [physics continuum] select the following models:


Group Box	Model
Space	Any
Time	Any
Material	Any single- or multi-component material model except Multi-Component Solid
Flow	Coupled Flow or Segregated Flow (for fluids only)
Optional Models	For solids, select one of: Segregated Solid Energy Coupled Solid Energy For fluids with Segregated Flow, select one of: Segregated Fluid Temperature Segregated Fluid Isothermal Segregated Fluid Enthalpy For fluids with Coupled Flow, select Coupled Energy.
Equation of State	Any
Viscous Regime	Any (for fluids only)
Optional Models	Radiation Surface Materials (selected automatically). See Surface Materials Model Reference.
Radiation	Select one of: Participating Media Radiation (DOM). See Participating Media Radiation (DOM) Model Reference Participating Media Radiation (Spherical Harmonics). See Participating Media Radiation (Spherical Harmonics) Reference. Volumetric Photon Monte Carlo (VPMC). See Volumetric Photon Monte Carlo (VPMC) Model Reference.
Radiation Spectrum (Participating)	Select one of: To model wavelength-independent radiation properties, select Gray Thermal Radiation. See Gray Thermal Radiation Model Reference. To model wavelength-dependent radiation properties, select Multiband Thermal Radiation. See Multiband Thermal Radiation Model Reference. If you want to combine participating media radiation with gaseous combustion, select k-Distribution Thermal Radiation. This model is a refinement of the Weighted Sum of Gray Gases Method (WSGGM). Not compatible with Volumetric Photon Monte Carlo (VPMC). See k-Distribution Thermal Radiation Model Reference.
Refraction (Gray) or Refraction (Multiband)	For Participating Media Radiation (DOM): Refraction (Gray) or Refraction (Multiband). For Volumetric Photon Monte Carlo (VPMC): Refraction (Gray) or Refraction (Multiband) is selected automatically. See Gray and Multiband Refration Model References.

Set the specifics of the participating media model:

选项	描述
Participating Media Radiation (DOM)	Set the order of the Ordinate Sets property to specify the desired degree of accuracy in simulating the participating media radiation effect. See Participating Media Radiation (DOM) Properties. Set the Under-Relaxation Factor and other properties for the DO Radiation solver. See The DO Radiation Solver.
Participating Media Radiation (Spherical Harmoncis)	Select the boundary secondary gradients for radiation and/or the interior secondary gradients at mesh faces. See Participating Media Radiation (Spherical Harmonics) Properties. Set the Secondary Gradients property for the Spherical Harmonics radiation solver. See Spherical Harmonics Radiation Solver Properties.
Volumetric Photon Monte Carlo (VPMC)	Set the child node properties for the Volumetric Photon Monte Carlo solver. See Volumetric Photon Monte Carlo Solver Properties.

Set the radiative properties of the medium lying between the radiating boundaries. For example, select Models > Gas > Air > Material Properties and set Absorption Coefficient, Scattering Coefficient, and (if a refractive model is active) Refractive Index. See Participating Media Radiation (DOM) Material Properties.
If two regions of same continuum are interfaced, place either a baffle or a porous baffle between them where both interface boundaries are actively participating in radiation. If the interface does not participate, use an internal interface.
To produce a semi-transparent interface, make sure that the same spectral model is used on both sides—both Gray or both Multiband.
Specify thermal radiation properties on boundaries and interfaces.
Identify the boundaries of your model where diffuse radiation enters and activate diffuse radiation at boundaries where it is needed:
1. At each boundary, select the Physics Conditions > Radiation Flux Option node.
2. Set the Radiation Flux Option property to Diffuse radiation flux.
3. Select the Physics Values > Diffuse Radiation Flux node.
4. Set the Method and Value properties. The flux is specified as a scalar profile.
  If you are using the Multiband Thermal model and the Diffuse Radiation Flux node has Method set to Composite, there is a node for each band under Diffuse Radiation Flux. Set the physics values for each band.
Set Thermal Environment > Radiation Temperature to a single value for all continua.