Practical three-dimensional electromagnetic modeling has traditionally been hampered by insufficient computing power. Recent advances in computer hardware are beginning to remove this difficulty, and one can expect that this trend will continue for the foreseeable future. To exploit this increased computer power and to solve more realistic problems, researchers have developed numerous algorithms appropriate for 3-D calculations and have built large general-purpose computer codes around them. In spite of this technical and theoretical progress, two practical difficulties remain: providing the computer code with an accurate description of a particular problem and viewing the end results of the calculation. Researchers at the Lawrence Livermore National Laboratory have been developing and using a new finite-difference, time-domain (FDTD) code over the last few years. This code, TSAR, is currently being used on a wide range of electromagnetic scattering, coupling, and propagation problems. Some of the geometries of interest are large and quite detailed, requiring meshes with more than a million cells. To efficiently deal with these large problems, we have developed a set of pre and post-processing tools to be used in conjunction with the TSAR FDTD code. This set of utilities consists of a solid-model based mesh generator, a mesh verifier, and …

We investigate the electromagnetic penguin contribution to /epsilon//prime///epsilon/ when the top quark mass is large. We find it depends sensitively on the top quark mass. 6 refs., 2 figs.

Several test problems are presented for evaluating the radiation diffusion equations. For spatial transport schemes, 1-D problems with known analytic solutions are tested on 2-D domains with non-orthogonal meshes. It is shown that a scheme based on the Finite Element Method is insensitive to grid distortions when the diffusion term is dominant. Other test problems deal with Compton scattering, specifically the 1-D Fokker-Planck equation coupled to an equation describing the change in electron temperature. The test problems model the evolution of a Planckian radiation field as it equilibrates with the electrons. In all cases, the numerical results are compared with the analytic ones. 15 refs., 9 figs., 7 tabs.