A three dimensional multi-grid FDTD code for modeling microwave sintering of materials

Computer modeling and simulation provide a valuable tool for characterizing complex electromagnetic (EM) devices and for developing fundamental understanding in the applications which involve complex electromagnetic interactions such as the biological effects of EM radiation and the microwave sintering of ceramics. In the area of microwave processing of materials, continued numerical modeling efforts are expected to aid in the scale-up and commercialization of this new technology. We describe the development of a three dimensional multi-grid FDTD code to help focus large number of cells around the desired region of interest. Solution procedures are described and some test geometries were solved using a uniform grid and the developed multi-grid codes to help validate the results from the developed code. Results from these comparisons, as well as the results of comparisons between the developed FDTD code and another available variable mesh code are presented. In addition, results from the simulation of realistic microwave sintering experiments showed improved resolution in critical sites inside the three dimensional sintering cavity. With the validation of the FDTD code, simulations for electrically large multimode microwave sintering cavities with multiple layers of samples were carried out to fully demonstrate the advantages of the developed multi-grid FDTD code.