﻿ Tech Briefs
 Microwave Heating Microwave heating of materials is extensively used in households and in industries. In this process, the electromagnetic field operates in the high frequency range of 300 MHz to 300 GHz, with electromagnetic scattering and absorption as well as reflection. In this Brief, we illustrate the use of ADINA-EM in simulating the microwave heating of a material sample in an oven, see Figure 1. Figure 1  Microwave oven First, we study the two-dimensional electromagnetic resonance in the oven without the sample. The plots in Figures 2 to 4 show magnetic (imaginary component) and electric (real component) field intensities for high excitation frequencies. It is also interesting to note that we can perform a frequency sweep in ADINA-EM, from low to high frequencies, for a same model in a single simulation. The movie above shows electromagnetic field modes in the cavity at different frequencies calculated in a single frequency sweep. Figure 2 2D electromagnetic fields: magnetic field intensity (left) and electric field intensity (right) at the excitation frequency of 2.2 GHz Figure 3 2D electromagnetic fields: magnetic field intensity (left) and electric field intensity (right) at the excitation frequency of 2.45 GHz; note the resonance in the oven Figure 4 2D electromagnetic fields: magnetic field intensity (left) and electric field intensity (right) at the excitation frequency of 2.7 GHz Next, we model in three dimensions the microwave heating of the sample. Figures 5 and 6 show magnetic and electric field intensities in the oven on a cutting plane. The band plots of the magnetic and electric fields show the effect of scattering due to the presence of the sample in the oven. The 3D movie shows the temperature in the material sample changing in time during the process of microwave heating. It can be seen that the material sample is heated very uniformly — like we would like our food to be heated, and like it is desirable in material processing or ceramics to prevent cracking. Figure 5  3D microwave heating: magnetic field intensity, real part (left) and imaginary part (right) Figure 6 3D microwave heating: electric field intensity, real part (left) and imaginary part (right) There are many exciting applications of ADINA-EM. For an introduction to ADINA-EM with more applications, please see here. Reference J. Clemens and C. Saltiel, "Numerical modeling of materials processing in microwave furnaces", Int. J. Heat Mass Transfer, Vol. 39, No. 8, pp. 1665-1675, 1996. Keywords: Electromagnetics, microwave, radiation, heating, material processing, wave guide, scattering, reflection, absorption, resonance, cavity, furnace, oven, frequency sweep