A vortex ring, also called a toroidal vortex, is a doughnut shaped vortex in a fluid; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal.
Vortex rings are plentiful in turbulent flows of liquids and gases, but are rarely noticed unless the motion of the fluid is revealed by suspended particles—as in the smoke rings which are often produced intentionally or accidentally by smokers. Fiery vortex rings are also a commonly produced by fire eaters. Visible vortex rings are also formed by the firing of certain artillery, in mushroom clouds, and in microbursts.
A vortex ring usually tends to move in a direction that is perpendicular to the plane of the ring and such that the inner edge of the ring moves faster forward than the outer edge. Within a stationary body of fluid, a vortex ring can travel for relatively long distance, carrying the spinning fluid with it.
Famous quotes containing the words vortex and/or ring:
“The Image is more than an idea. It is a vortex or cluster of fused ideas and is endowed with energy.”
—Ezra Pound (1885–1972)
“I started out very quiet and I beat Turgenev. Then I trained hard and I beat de Maupassant. I’ve fought two draws with Stendhal, and I think I had an edge in the last one. But nobody’s going to get me in any ring with Tolstoy unless I’m crazy or I keep getting better.”
—Ernest Hemingway (1899–1961)