FDTD in curvilinear coordinates using a rectangular FDTD formulation

In the simplest formulation, the FDTD algorithm requires that objects follow the rectangular grid. For curved surfaces, this is a severe limitation. In this paper, an approach to modify an existing rectangular FDTD code to model structures more naturally described in another coordinate system is demonstrated. The approach is a modification to the update coefficients and does not require significant changes to an existing piece of software.