Gap radiation supports 2D or 3D target. It has 2 application regions. The master region can be 2D or 3D, and the slave region can be 2D or 3D.

Gap radiation has four combinations of “input data” and “input material”. Emissivity can be assigned separately to each application region. When the MLI material is referred, the arithmetic nodes will be generated to represent MLI nodes. When the coating material is used, no arithmetic nodes are created, but more parameters are transferred into the radiation codes. Gap radiation does not support spatial fields because a similar method is used as the contact load.