Application of a Finite-Volume Time-Domain Maxwell Equation Solver to Three-Dimensional Objects

摘要

Concurrent engineering approaches for the disciplines of computational fluiddynamics (CFD) and electromagnetics (CEM) are necessary for designing future high-performance, low-observable aircraft. A characteristic-based finite-volume time-domain (FVTD) computational algorithm, developed for CFD and now applied to CEM, is implemented to analyze the radar cross section (RCS) of two three-dimensional objects, the ogive and cone-sphere. The FVTD formulation implements a Monotone Upstream-Centered Scheme for Conservation Laws (MUSCL) algorithm for the flux evaluation and a Runge-Kutta multi-stage scheme for the time integration. Developmental FVTD work for the thesis focused on algorithm development to analyze scattering and obtain RCS data for closed-surface perfect electric conductor (PEC) 3-D objects using either a Gaussian pulse or sinusoid incident wave. In addition, specification of the direction and polarization of the incident wave gives monostatic and bistatic RCS results. Convergence and threshold checks end the simulation run to ensure accurate computation of the RCS. Validation of the characteristic-based FVTD formulation and code for electromagnetic scattering problems is completed by comparing RCS results obtained from the FVTD code to Moment Method and empirical RCS data. The FVTD results for the ogive and cone-sphere are within 3.0 dB of the MoM results and 3.1 dB of the empirical RCS results. Accurate FVTD computations of diffraction, traveling waves, and creeping waves require a surface grid point density of 15-30 cells/lamda.