Temperature rise evaluation in human body exposed to RF energy is becoming increasingly important topic related to the future development of the RF exposure safety standards. Therefore the validation of the existing methods like FDTD used in such complex multidisciplinary studies is very important. The accuracy of the FDTD solution of the Bio-Heat equation [4] which is most often used in this type if studies has been analyzed based on the developed program package [1-2]. The effect of stair case geometry representation in FDTD grid has been investigated by comparing the test case with analytical solution [8]. In addition comparison was made with the published results [9]. Preliminary data show that in case of constant temperature boundary conditions FDTD results slightly differ from the analytical solution during the transition state of the heat transfer process while there is a much better agreement in steady state regime. In case of convective boundary conditions the steady state temperature distribution at the convective boundary obtained by FDTD method also differ insignificantly from the FEM results reported in literature and temperature values inside the model are almost identical with that from FEM models. The results point to the conclusion that the error in FDTD simulations may be attributed to faster heat exchange which is due to the difference of surface area between the smooth and stair case boundaries of the modeled structures. These results are similar to those reported in [9]. The impact on temperature inside the body far from the boundary is less than 1% while at the boundary is in the range of 4-7% for the models with 0.5 mm grid resolution and tissue like thermal properties.
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