Although the heat transfer interfaces only solve for the energy equation, the context leading to Equation 4-13 does account for the three additional conservation laws that complete the Continuum Mechanics theory:

The equations corresponding to each of them are recalled below in Table 4-1. For more details about the theory of Solid and Fluid Mechanics, see the Structural Mechanics Module User’s Guide and CFD Module User’s Guide.

When modeling a heat transfer problem with one of the Heat Transfer interfaces, the aforementioned laws needs to be respected. For example, the velocity field, u, provided in the energy equation and responsible for convection in a fluid, should satisfy the continuity equation here below in order to avoid unphysical results.