Vortex

Not to be confused with vertex. For other uses, see Vortex (disambiguation).
Vortex created by the passage of an aircraft wing, revealed by colored smoke
Vortices formed by milk when poured into a cup of coffee
A Kármán vortex street is demonstrated in this photo, as winds from the west blow onto clouds that have formed over the mountains in the desert. This phenomenon observed from ground level is extremely rare, as most cloud-related Kármán vortex street activity is viewed from space

In fluid dynamics, a vortex (pl.: vortices or vortexes)[1][2] is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved.[3][4] Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in the wake of a boat, and the winds surrounding a tropical cyclone, tornado or dust devil.

Vortices are a major component of turbulent flow. The distribution of velocity, vorticity (the curl of the flow velocity), as well as the concept of circulation are used to characterise vortices. In most vortices, the fluid flow velocity is greatest next to its axis and decreases in inverse proportion to the distance from the axis.

In the absence of external forces, viscous friction within the fluid tends to organise the flow into a collection of irrotational vortices, possibly superimposed to larger-scale flows, including larger-scale vortices. Once formed, vortices can move, stretch, twist, and interact in complex ways. A moving vortex carries some angular and linear momentum, energy, and mass, with it.

  1. ^ "vortex". Oxford Dictionaries Online (ODO). Oxford University Press. Archived from the original on February 3, 2013. Retrieved 2015-08-29.
  2. ^ "vortex". Merriam-Webster Online. Merriam-Webster, Inc. Retrieved 2015-08-29.
  3. ^ Ting, L. (1991). Viscous Vortical Flows. Lecture notes in physics. Springer-Verlag. ISBN 978-3-540-53713-7.
  4. ^ Kida, Shigeo (2001). Life, Structure, and Dynamical Role of Vortical Motion in Turbulence (PDF). IUTAMim Symposium on Tubes, Sheets and Singularities in Fluid Dynamics. Zakopane, Poland.