Accession Number : AD0290228

Title :   MOTION OF A PAIR OF VORTICES BEHIND A CYLINDER

Corporate Author : NAVAL WEAPONS LAB DAHLGREN VA

Personal Author(s) : VIBRANS,GERWIG

Report Date : 05 NOV 1962

Pagination or Media Count : 1

Abstract : An unexpectedly high drag which develops when a body is accelerated in a fluid of low viscosity has been thought to be related to the vortex ring or vortex pair which seems to develop behind such a body. The ideal flow pattern of a vortex pair, while travelling in equilibrium with a cylinder, and the forces on the cylinder are calculated for a number of examples, which include the general case of unsymmetric configurations. The motion of the vortices is investigated in the case where they are slightly displaced from the equilibrium position. An increase of flow velocity induces an oscillatory movement, and an oscillating force acts on the cylinder. If a programmed acceleration leads to a new stationary flow, then the net effect of the vortices is to diminish the induced mass. Even when the vortex strength is assumed to increase, there is apparently a decrease in induced mass. (Author)

Descriptors :   *CYLINDRICAL BODIES, *DRAG, *FLUID MECHANICS, *HYDRODYNAMICS, *UNDERWATER BALLISTICS, *VORTICES, OSCILLATION, PARTIAL DIFFERENTIAL EQUATIONS

Distribution Statement : APPROVED FOR PUBLIC RELEASE