A Parallel Finite-Volume Runge-Kutta Algorithm for Electromagnetic Scattering

A 3D explicit finite volume algorithm has been developed to simulate scattering from complex geometries on parallel computers using structured body conformal curvilinear grids. Most simulations for practical 3D geometries require a large number of grid points for adequate spatial resolution making them suitable to parallel computation. The simulations have been carried out using a multi-block/zonal approach in the message passing paradigm on the SP-2. Each zone is placed on a separate processor and inter-processor communication is carried out using the Message Passing Library/Interface (MPL/MPI). Integration of Maxwell's equations is performed using the four-stage Runge-Kutta time integration method on a dual grid. This method of integrating on a staggered grid gives enhanced dissipative and dispersive characteristics. A scattered field formulation has been used and the Liao boundary condition is used at the outer nonreflecting boundary. The far zone transformation has also been implemented efficiently, using specialized MPL functions to evaluate the far zone scattering results. Results show extremely good comparisons for scattering from the sphere and the ogive with the exact solution and standard FDTD type algorithms. Comparisons for nonaxisymmetric targets like the NASA almond with experimental data has also been found to be extremely good.