Transparent boundary conditions in a Discontinuous Galerkin Trefftz method
This work addresses the problem of artificial boundary reflections in computational electromagnetics, offering a more accurate and efficient boundary condition for wave propagation simulations.
The paper introduces a new type of transparent boundary condition for a discontinuous Galerkin Trefftz method that reduces parasitic reflections in electromagnetic wave simulations. Numerical tests show spectral convergence and dissipative behavior, outperforming first-order absorbing boundary conditions.
The modeling and simulation of electromagnetic wave propagation is often accompanied by a restriction to bounded domains which requires the introduction of artificial boundaries. The corresponding boundary conditions should be chosen in order to minimize parasitic reflections. In this paper, we investigate a new type of transparent boundary condition for a discontinuous Galerkin Trefftz finite element method. The choice of a particular basis consisting of polynomial plane waves allows us to split the electromagnetic field into components with a well specified direction of propagation. The reflections at the artificial boundaries are then reduced by penalizing components of the field incoming into the space-time domain of interest. We formally introduce this concept, discuss its realization within the discontinuous Galerkin framework, and demonstrate the performance of the resulting approximations by numerical tests. A comparison with first order absorbing boundary conditions, that are frequently used in practice, is made. For a proper choice of basis functions, we observe spectral convergence in our numerical test and an overall dissipative behavior for which we also give some theoretical explanation.