BCs in a coupled problem

Consider a thermo-mechanical coupled problem, where coupling exists from both the sides, mechanical loading producing thermal effects and vice versa. In such a case, is it necessary to always prescribe a thermal boundary condition along with a mechanical boundary condition on the same boundary for the problem to give valid results?

For example, when prescribing mechanical load with temperature or prescribing heat flux with displacement.

• Boundary conditions are specific to individual equations. Care to share the model you're considering in formulas? – Wolfgang Bangerth Nov 21 '15 at 1:46
• I agree with @WolfgangBangerth, the BCs you apply should match whatever physical situation you're trying to model. Often BCs for different physics will be applied at the same location, but this is not always the case. Consider internal fluid flow in a pipe with heat transfer. BCs for the fluid are likely applied on the interior of the pipe while BCs for heat transfer are likely applied on the exterior of the pipe. – Charles Apr 26 '16 at 1:43

• What type of BC you use (Dirichlet, Neumann, Robin) and where you apply it depends on what you are modeling -- remember, you can apply BC's at $\infty$