surface boundary layer

例句：

1. 1.The surface boundary layer is a critical region where the air and water molecules interact.
   表面边界层是空气和水分子相互作用的关键区域。
2. 2. In the surface boundary layer, the temperature gradient is steeper than in the free stream.
   在表面边界层中，温度梯度比自由流中的要陡峭。
3. 3.The study of the surface boundary layer is essential for understanding the behavior of fluids in complex geometries.
   研究表面边界层对于理解流体在复杂几何结构中的行为至关重要。