Vortex tube

Japanese: 渦管 - うずかん

...Generally, vortex filaments either terminate at a boundary or form a loop, but do not break within the fluid.
[Vortex tube]
If you imagine a closed curve in the flow and draw vortex lines through each point on it, a tube will be created. This is called a vortex tube, and the thin parts of this are vortex filaments.

From [Flow]

...In particular, the curves created by connecting the rotation axes of fluid particles one after another are called vortex lines. Also, a tube created by vortex lines passing through each point of a small closed curve taken in a flow with vortices is called a vortex tube. If you take an arbitrary surface in a fluid, the fluids on both sides exert forces on each other through that surface. ...

*Some of the terminology that refers to "vortex tubes" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…一般に渦糸は境界で終わるか，輪を作るかのいずれかであって，流体の中で切れることはない。
［渦管］
　流れの中に閉曲線を考え，その上の各点を通って渦線を引くと一つの管ができる。これを渦管といい，これの細いものが渦糸である。…