Shape perturbation of a nonlinear mixed problem for the heat equation

Abstract

We consider the heat equation in a domain that has a hole in its interior. We impose a Neumann condition on the exterior boundary and a nonlinear Robin condition on the boundary of the hole. The shape of the hole is determined by a suitable diffeomorphism $\varphi$ defined on the boundary of a reference domain. Assuming that the problem has a solution $u_0$ when $\varphi$ is the identity map, we demonstrate that a solution $u_{\varphi }$ continues to exist for $\varphi$ close to the identity map and that the "domain-to-solution" map $\varphi \mapsto u_{\varphi }$ is of class $C^{\infty }$. Moreover, we show that the family of solutions $\{u_{\varphi }{\}}_{\varphi }$ is, in a sense, locally unique. Our argument relies on tools from Potential Theory and the Implicit Function Theorem. Some remarks a the linear case complete the paper.