A coupling strategy for nonlocal and local diffusion models with mixed volume constraints and boundary conditions

We develop and analyze an optimization–based method for the coupling of nonlocal and local diffusion problems with mixed volume constraints and boundary conditions. The approach formulates the coupling as a control problem where the states are the solutions of the nonlocal and local equations, the objective is to minimize their mismatch on the overlap of the nonlocal and local domains, and the controls are virtual volume constraints and boundary conditions. We prove that the resulting optimization problem is well–posed and discuss its implementation using Sandia’s agile software components toolkit. The latter provides the groundwork for the development of engineering analysis tools, while numerical results for nonlocal diffusion in three–dimensions illustrate key properties of the optimization–based coupling method.