LINK31: Radiation Link Element

Used for simple problems involving radiation between two points or several pairs of points.

SURF151 and SURF152: Surface-effect Elements

Used for radiation between a surface and a point.

Radiosity Solver Method

For more general radiation problems involving two or more surfaces, the radiosity method is the preferred solution method. This method is supported by all 3D/2D elements having a temperature degree of freedom. It solves separately for the temperature and the radiative heat flux and enables temperature dependent material properties (see Solving for Temperature and Radiosity). The decoupled solution process makes the radiosity method more memory efficient and therefore more suitable for large models than the alternative radiation matrix method. While the radiosity solution is valid for both steady-state and transient analyses, convergence difficulties may arise in some situations. For example, sufficiently high heat generation in the model can lead to convergence difficulties in a steady-state thermal analysis and would require a transient analysis to achieve a converged solution. For more information, see also Using the Radiosity Solver Method and Radiosity Solution Method in the Theory Reference.

AUX12 Radiation Matrix Method

The radiation matrix method also solves general radiation problems involving two or more surfaces. This method generates a matrix of conductances between radiating surfaces and uses the matrix as a superelement in the thermal analysis. With the radiation matrix method, temperature and flux are fully coupled so iteration is not required. The matrix is constructed only once. It requires more memory than the radiosity method and does not account for temperature dependent emissivity. It can be useful in problems where most heat transfer occurs by radiation, and conduction and convection are relatively insignificant. For more information, see also Using the AUX12 Radiation Matrix Method and Radiation Matrix Method in the Theory Reference.