Gray and Multiband Refraction Model References

The Refraction models calculate optical refraction at boundaries between a continuum and the environment and at interfaces between continua.

There are two Refraction models, Refraction (Gray) and Refraction (Multiband), which require the Gray Thermal Radiation model or the Multiband Thermal Radiation model respectively. The thermal radiation models require the Participating Media Radiation (DOM) model.

The Refraction models do not calculate refraction between phase interfaces, nor do they apply to periodic or mapped interfaces. Symmetry and periodic boundaries contribute to the radiation heat transfer only by reflecting or periodically transforming the radiative energy in the correct direction. Both types of boundaries are compatible with post-processing of DOM radiation and refraction.

Lack of sufficient angular discretization degrades accuracy, so that refraction modeling with DOM is incompatible with ordinate set S2. If S2 is used in set up with DOM and refraction, the model automatically resets this to S4 and displays a warning message in the output window. Use S8 or higher for good accuracy. See Participating Media Radiation (DOM) Properties.

Use a Refraction model in regions where one or more boundaries are transparent or semi-transparent. Any interface boundary where the other side does not use DOM acts as an external boundary and can be set as transparent or semi-transparent. A fluid film boundary is a possible example. For these transparent and semi-transparent boundaries, the environment is modeled as a blackbody, an energy sink, into which radiation can escape.