 ) and choose the pairs to add from the list in the Add dialog box that opens; then click OK. A pair has to be created first. See Identity and Contact Pairs in the COMSOL Multiphysics Reference Manual for more details.
) and choose the pairs to add from the list in the Add dialog box that opens; then click OK. A pair has to be created first. See Identity and Contact Pairs in the COMSOL Multiphysics Reference Manual for more details.| • | For General source enter a value for the boundary heat source Qb when the default option, User defined, is selected. | 
| • | For Heat rate enter the heat rate Pb. In this case Qb = Pb ⁄ A, where A is the total area of the selected boundaries. | 
 ) and select Advanced Physics Options in the Show More Options dialog box.
) and select Advanced Physics Options in the Show More Options dialog box.| To define the boundary heat source Qb as a function of the temperature, use the local temperature variable on the selected boundary, ht.bhs1.Tvar, that corresponds to the appropriate variable (upside, downside, or average temperature of a layer, wall temperature with turbulence modeling), depending on the model configurations. | 
| Upside and downside settings can be visualized by plotting the global normal vector (nx, ny, nz), that always points from downside to upside. Note that the normal vector (ht.nx, ht.ny, ht.nz) may be oriented differently. |