High Order Weighted Extrapolation for Boundary Conditions for Finite Difference Methods on Complex Domains with Cartesian Meshes

The design of numerical boundary conditions is a challenging problem that has been tackled in different ways depending on the nature of the problem and the numerical scheme used to solve it. In this paper we present a new weighted extrapolation technique which entails an improvement with respect to the technique that was developed in [1]. This technique is based on the application of a variant of the Lagrange extrapolation through the computation of weights capable of detecting regions with discontinuities. We also present a combination of the above technique with a least squares approach in order to stabilize the scheme in some cases where Lagrange extrapolation can turn the scheme mildly unstable. We show that this combined extrapolation technique can tackle discontinuities more robustly than the procedure introduced in [1].