A Hybrid Method of Higher-Order FDTD and Subgridding Technique

A hybrid method of higher-order finite-difference time-domain (FDTD) method and subgridding technique is proposed in this letter. The whole computational domain is decomposed into two kinds of regions. One is coarse-grid higher-order region, and another is fine-grid low-order region. An interlayer is introduced to connect the two kinds of regions. The update schemes for fields in each region and in the interlayer are given. Different time-steps are used in the higher-order region and in the subgridding region to further improve computational efficiency. Numerical properties in terms of nonphysical interface reflection and late-time stability are numerically studied. Numerical examples are also given to validate the efficiency and accuracy of this method.