跑双向fsi过程中遇到的错误和也许可行的解决方案

1. static structural - warning

2. transient structural - 高度扭曲（highly distorted）

解决方法：来自 https://www.youtube.com/watch?v=fI2a_xP0veI

①网格

physics preference >>> non-linear mechanical

element order >>> linear

②考虑网格自适应

③合理设置网格一开始的长宽比，使最后的变形网格长宽比接近1 

（materials that are being uniformly stretched or compressed can benefit from changing the original aspect ratio to prevent excessive aspect ratios once deformed）

④开auto time stepping