What is a vortex in fluid dynamics?

A vortex is a region in a fluid where the flow revolves around a straight or curved axis line. These rotational structures occur naturally in stirred fluids, smoke rings, whirlpools, tornadoes, and tropical cyclones. Once formed, vortices can move, stretch, twist, and carry angular and linear momentum, energy, and mass.

What we know

• A vortex is defined as a region in a fluid where the flow revolves around a straight or curved axis line. [1, 2]
• In most vortices, the fluid flow velocity is greatest next to its axis and decreases in inverse proportion to the distance from the axis. [2]
• Viscous friction within a fluid tends to organize flow into a collection of irrotational vortices in the absence of external forces. [2]
• A moving vortex carries mass, energy, linear momentum, and angular momentum along with it. [2]

Where to go next

• a case in pointWhat is a toroidal vortex ring?
• how it workedHow does the Rankine model describe a vortex?
• the bigger pictureHow are fluid flows simulated with computers?
• how we knowWhat forms whirlpools and tornadoes?
• whoWho discovered the Rankine vortex model?
• an unexpected connectionHow do fire eaters produce vortex rings?Fiery vortex rings are formed as visual tricks by performers, connecting abstract fluid dynamics directly to performance art.

Sources

• [1]vortex (Wikidata Q732722) · CC0 1.0
• [2]Vortex · CC BY-SA 4.0
• [3]Vortex ring · CC BY-SA 4.0
• [4]Rankine vortex · CC BY-SA 4.0
• [5]Computational fluid dynamics · CC BY-SA 4.0