Matrix-Free Time-Domain Method with Unconditional Stability in Unstructured Meshes

We develop an unconditionally stable matrix-free time-domain method for analyzing general electromagnetic problems discretized into arbitrarily shaped unstructured meshes. This method does not require the solution of a system matrix, no matter which element shape is used for space discretization. Furthermore, this property is achieved irrespective of the time step used to perform the time domain simulation. As a result, the time step can be solely determined by accuracy regardless of space step. Numerical experiments have validated the accuracy and efficiency of the proposed new method.