On the approximation error in the problems of conjugate convective heat transfer

The effects of small boundary perturbation on the approximation error for a model boundary value problem are considered. It is shown that the ignorance of small perturbations of the boundary leads to an additional approximation error in the original differential problem. This error is independent of mesh size. The obtained results are of interest for the mathematical modeling of conjugate heat transfer, the modeling of flows with surface chemical reactions and other applications related to fluid flows near rough surfaces.