Experiments on Unstable Vortices

by Enzo Levi, Researcher; Instituto de Ingeniería, Universidad Nacional Autónoma de México, México, D.F., Mexico,

Serial Information: Journal of the Engineering Mechanics Division, 1972, Vol. 98, Issue 3, Pg. 539-559

Document Type: Journal Paper


Unlike wake vortices, drain and inlet vortices cannot be explained as being friction effects. It is suggested that vortices of this type are the result of an unstable process, which starts when an accelerated or decelerated jet abuts on a body of quiescent fluid. This hypothesis is corroborated as follows. At first it is shown that, if it is satisfied, a part of the momentum flux of the jet gives rise to the centripetal force acting inside the vortex and a suitable relationship between jet and vortex characteristic parameters is deduced. Then it is verified that this relationship is in fact fulfilled by three different experimental vortices: those produced in a tank by a jet issued from a vertical and from a slanted nozzle, respectively, and that arising behind a rectangular orifice, set across a laboratory channel. The mechanism that produces tornadoes is explained. Some traditional beliefs concerning vortices are criticized from this new point of view.

Subject Headings: Vortices | Drainage | Inlets (waterway) | Friction | Parameters (statistics) | Verification | Tornadoes

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