说明：  COMSOL为复杂科研仿真提供了友好的弱形式界面，类似于PDE方程，但相关手册至今未汉化，这是目前能找到的比较好的入门资料了。
(COMSOL for the complex scientific simulation provides a friendly weak form interface, similar to the PDE equation, but the relevant manual has not finished, which is now able to find a better entry information.)