Perfect thermal contact

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Perfect thermal contact occurs when a solid is in contact with the environment or with another solid in such a way that there is no temperature difference and no extra resistance to heat flow at the boundary. At the boundary surface A, the temperatures on both sides are equal and the heat flux across the boundary is continuous. Let T be the solid’s boundary temperature and T_e the environment’s (or the neighboring solid’s) boundary temperature; k and k_e are the thermal conductivities of the solid and the other material; and n is the normal to the surface. If there is heat generation at the boundary (for example from sliding friction), this boundary condition is modified to include q, the heat produced per unit area.