如果取一个有旋的向量场，流体流动方向是环绕某个坐标轴的，那么就会发现它的散度是零。

And, if you take a vector field where maybe everything is rotating, a flow that's just rotating about some axis, then you'll find that its divergence is zero.

youdao

这次有一些发酵了，但我必须一直不停地搅啊搅以便尝出中和的味道，因为椰奶不断地一团团旋到水面，而清水一直留于杯底。

It cultured a little bit, but I had to keep stirring it to taste it. The coconut milk kept rising to the top in little clumps, and the water settled to the bottom.

youdao

假如力场中某处有一小块固体，旋度度量的是固体在力场中的旋转程度，在力场里来观察。

If you have a small solid somewhere, the curl will just measure how much your solid starts spinning if you leave it in this force field.

youdao

And since we don't know the absolute up and down in the universe, it is possible that some of the electrons may be spinning up.

由于我们在宇宙里,并不知道什么是绝对的上和下，所以说上面的现象很有可能是,一些电子向上自旋引起的。

麻省理工公开课 - 固态化学导论课程节选