Solver Physics of Ansys Lumerical DGTD — Lesson 1

The DGTD Method

The Discontinuous Galerkin Time-Domain (DGTD) method rigorously solves Maxwell’s equations in the time domain. In this video lesson, you will learn the basics of the DGTD method.

DGTD vs. FDTD

In this video lesson, you will learn about the differences between the DGTD and FDTD solvers as well as their similarities as time-domain optical solvers.

 

One of the differences that users might notice between DGTD and FDTD is the results returned by Frequency domain field and power (DFT) monitors. While in FDTD, DFT monitors return one result for the power flux transmitted through the monitor (T), in DGTD these monitors return two power flux results named "T_front" and "T_back" as shown in the following screenshot. These values represent the power flux calculated based on the field intensities immediately at the front and back sides of the monitor within the mesh grid. This is due to the way the DGTD algorithm works and, in most cases, the values returned are very close to each other and users can simply take one of the values as a reference for comparison in their convergence testing or other applications.