variable free-stream velocity

例句：

1. 1.The aircraft's free-stream velocityis measured in knots.
   飞机的自由流速度以节为单位测量。
2. 2. Thewind speed at the coastline is much higher than thefree-stream velocity of the river.
   海岸线处的风速远高于河流的自由流速度。
3. 3. The turbulence inthe wake of the ship causes a decreasein the free-stream velocity.
   船只尾迹中的湍流会导致自由流速度降低。