Late-time Instability for UPML and Periodic Boundary in Elongated Multilayer Thin Plate Simulations

Abstract

In this article, we examine the late-time instability properties of hybrid boundary conditions in the discontinuous Galerkin time-domain (DGTD) simulations of an elongated multilayer thin plate. The hybrid boundary is combined by uniaxial perfectly matched layer (UPML) and periodic boundary condition (PBC). Herein, the PBC is employed to approximate an infinite long target. For the target studied, when implementing the UPML within the discrete DGTD domain, late-time instabilities would occur. These instable or spurious information can severely corrupt the solution of a physical problem in time domain. To suppress them, two effective ways are proposed, i.e., increasing the size of the air space (the distance away from the interface between the target studied and the UPML) and decreasing the conductivity of the UPML. The numerical experiments verify that the instability characteristics can be efficiently attenuated by proposed two methods in this paper.