Improved Estimation of Time Step Bound for Discontinuous Galerkin Time-Domain Method

In this letter, an improved approach for the estimation of time step bound in the discontinuous Galerkin time-domain (DGTD) method has been developed. Different from the widely used energy-based technique, the spectral radius of the system matrix in the proposed method is used to analytically derive the stability condition of the DGTD method. In order to accelerate the solution of the time step bound, the spectral radius of the local system instead of the global spectral radius is solved, and thus, the proposed elementwise estimation scheme is suitable for the practical large-scale problems. The numerical examples demonstrate that the maximal time step estimated by the proposed method is up to 0.95 times as large as the accurate one and up to 3.83 times as large as the one determined by the widely used energy technique.