scholarly journals Vortex ring dynamics at a free surface

1989 ◽  
Vol 1 (3) ◽  
pp. 449-451 ◽  
Author(s):  
L. P. Bernal ◽  
J. T. Kwon
Keyword(s):  
Free Surface ◽  
Vortex Ring ◽  
Ring Dynamics

Self‐induced vortex ring dynamics in subsonic rectangular jets

1995 ◽  
Vol 7 (10) ◽  
pp. 2519-2521 ◽  
Author(s):  
Fernando F. Grinstein
Keyword(s):  
Vortex Ring ◽  
Ring Dynamics

The mechanism of vortex connection at a free surface

1999 ◽  
Vol 384 ◽  
pp. 207-241 ◽  
Author(s):  
CHIONG ZHANG ◽  
LIAN SHEN ◽  
DICK K. P. YUE
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Vortex Ring ◽  
Stokes Equations ◽  
Incidence Angle ◽  
Surface Boundary ◽  
Viscous Layer ◽  
Vertical Vorticity ◽  
Vorticity Component ◽  
Stress Boundary Conditions

Vortex connections at the surface are fundamental and prominent features in free-surface vortical flows. To understand the detailed mechanism of such connection, we consider, as a canonical problem, the laminar vortex connections at a free surface when an oblique vortex ring impinges upon that surface. We perform numerical simulations of the Navier–Stokes equations with viscous free-surface boundary conditions. It is found that the key to understanding the mechanism of vortex connection at a free surface is the surface layers: a viscous layer resulting from the dynamic zero-stress boundary conditions at the free surface, and a thicker blockage layer which is due to the kinematic boundary condition at the surface. In the blockage layer, the vertical vorticity component increases due to vortex stretching and vortex turning (from the transverse vorticity component). The vertical vorticity is then transported to the free surface through viscous diffusion and vortex stretching in the viscous layer leading to increased surface-normal vorticity. These mechanisms take place at the aft-shoulder regions of the vortex ring. Connection at the free surface is different from that at a free-slip wall owing to the generation of surface secondary vorticity. We study the components of this surface vorticity in detail and find that the presence of a free surface accelerates the connection process. We investigate the connection time scale and its dependence on initial incidence angle, Froude and Reynolds numbers. It is found that a criterion based on the streamline topology provides a precise definition for connection time, and may be preferred over existing definitions, e.g. those based on free-surface elevation or net circulation.

Axisymmetric interaction between a vortex ring and a free surface

1994 ◽  
Vol 6 (1) ◽  
pp. 224-238 ◽  
Author(s):  
Peder A. Tyvand ◽  
Touvia Miloh
Keyword(s):  
Free Surface ◽  
Vortex Ring

scholarly journals The effect of a parallel free surface upon a submerged shallow synthetic jet

2020 ◽  
Author(s):  
Abhay Kumar ◽  
Ashish Karn
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Vortex Ring ◽  
Water Surface ◽  
Primary Objective ◽  
Synthetic Jet ◽  
Vortex Rings ◽  
Beam Laser ◽  
Jet Trajectory ◽  
Water Depths

The interaction of a submerged shallow synthetic jet with a parallel free surface has gathered substantial interest, owing to its relevance to the operation of marine vehicles viz. ships that move close to the water surface. However, despite exhaustive research on the perturbation on a free surface, very few studies have experimentally investigated the effect of unconfined water surface height on the evolution and propagation of a submerged synthetic jet. This study experimentally investigates a synthetic jet submerged in a quiescent flow at shallow depths ejecting parallel to the free surface, through qualitative analysis and quantitative measurements. The qualitative study includes the visualization of the flow using Plane Laser Induced Fluorescence (PLIF) technique, whereas the velocity measurements are carried out by a five-beam Laser Doppler Velocimetry (LDV) probe. The primary objective of these analysis and measurements is to gain a physical insight into the characteristics of vortex ring in a synthetic jet ejected from a fixed orifice at different water depths and at varying Reynolds number. Our studies indicate that the behavior of the vortex rings drastically changes as the depth of the jet crosses a certain threshold. Although no significant change in the path of synthetic jet is observed beyond a threshold depth in our experiments, the jet trajectory shows an interesting dependence on the Reynolds number based on circulation for shallow water depths. It has been found that in the shallow depths, the vortex ring drifts upwards and interacts with the free surface at lower Reynolds number, whereas for larger Reynolds number, the vortex ring rebounds near the free surface and moves downward. Based on our observations, it can be concluded that the phenomenon of upward/downward flection of vortex rings depends both upon its circulation and water depth.

Interaction of an obliquely rising vortex ring with a free surface in a viscous fluid

Meccanica ◽  
1996 ◽  
Vol 31 (6) ◽  
pp. 623-655 ◽  
Author(s):  
Samuel Ohring ◽  
Hans J. Lugt
Keyword(s):  
Free Surface ◽  
Viscous Fluid ◽  
Vortex Ring

The effect of ion drag on quantized vortex ring dynamics

1971 ◽  
Vol 35 (5) ◽  
pp. 311-312 ◽  
Author(s):  
M. Steingart ◽  
W.I. Glaberson
Keyword(s):  
Vortex Ring ◽  
Quantized Vortex ◽  
Ring Dynamics
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