On the superposition of a heat source and contact resistance
where 5 is the rate of heat generated per unit area at the interface, Hi is the rate of heat per unit area flowing into the corresponding medium and C< is a constant whose interpretation depends on the nature of the interface. Condition (2) is obtained by considering models of the interface in which either the contact resistance or the heat source is broken up into two parts. If the source is caused by friction as the two solids slide against each other with the interface as slip plane, these two models correspond respectively to lubricated and to dry friction.