Resolvent Limits of Exterior Boundary Value Problems and Singular Perturbation of Laplace Operator in 3D
摘要
In this work we study the Helmholtz equation with boundary condition in the exterior of a ball of radius \(\varepsilon \) in dimension 3, in the radial case. The boundary condition is the Robin condition with a power type weight. Taking the limit \(\varepsilon \rightarrow 0\) , we show that the solution of the problem doesn’t feel the initial hole, unless if the power of the weight is 1. In this case a singular perturbation appears and the resolvent behaves exactly like the resolvent of \(\Delta _\alpha \) , the Laplace operator with point-like interaction.