本文利用COMSOL Multiphysics分析非線性的凝固相變化問題、自然對流問題、對流凝固問題以及平板加熱器之均溫性分析問題。比較套裝軟體COMSOL Multiphysics對於非線性問題與不連續界面以及應用於實務設計時，其計算的精確度。本文先以具有解析解的相變化問題如史蒂芬問題、Rathjen問題來作分析比較。再針對溫度與流場耦合的自然對流與凝固對流問題，使用COMSOL進行熱流耦合運算，並分析其計算結果。最後進行實務設計的平板加熱器之均溫性分析，經由前次設計之實驗數據來反推其設計參數，進而對現有的加熱器進行改良。分析後發現，COMSOL在實務設計上求解相當便利，對於耦合問題上面亦具有優異的求解能力，但對於非線性的液固界面追蹤誤差較大。

Abstract
This study is to use the software package COMSOL Multiphysics to analyze the nonlinear solidification or phase-change problems, the natural convection problems, the coupling of convection and solidification problems and the thermal problems in the designed Susceptor. The accuracy of COMSOL for solving nonlinear and discontinuous interface problems and that of the practical design problem are compared and analyzed. First, the Stefan and Rathjen solidification problems with exact solutions are investigated by using COMSOL. Furthermore, COMSOL is employed to study the natural convection problems and the convection and solidification problems in which the temperature and flow fields are coupled with each other. Finally, COMSOL is applied to the heater design of a Susceptor for obtaining the uniform temperature distribution. Inverse calculation is utilized to acquire the design parameters from the experimental data of the previously designed Susceptor. The heater design is modified by the COMSOL analysis. From the analysis results, it can be found that COMSOL works very well for the heater design of the Susceptor and for solving the coupling problems. However, the location prediction of the solid/liquid interface of a solidified problem is not very accurate.

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