Concentration of vorticity due to selective decay in doubly periodic vortices and a vortex pair

Environmental crosswind can greatly affect the development of aircraft wake vortex pair. Previous numerical simulations and experiments have shown that the nonlinear vertical shear of the crosswind velocity can affect the dissipation rate of the aircraft wake vortex, causing each vortex of the vortex pair descent with different velocity magnitude, which will lead to the asymmetrical settlement and tilt of the wake vortex pair. Through numerical simulations, this article finds that uniform crosswind convection and linear vertical shear crosswind convection can also have an effect on the strength of the vortex. This effect is inversely proportional to the cube of the vortex spacing, so it is more intense on small separation vortex pair. In addition, the superposition of crosswind and vortex-induced velocities will lead to the asymmetrical pressure distribution around the vortex pair, which will also cause the tilt of the vortex pair. Furthermore, a new analysis method for wake vortex is proposed, which can be used to predict the vortex trajectory.

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Topological bifurcations of vortex pair interactions

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.191 ◽

2021 ◽

Vol 917 ◽

Author(s):

Anne R. Nielsen ◽

Morten Andersen ◽

Jesper S. Hansen ◽

Morten Brøns

Keyword(s):

Vortex Pair ◽

Pair Interactions

Abstract

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Instability and merging of a helical vortex pair in the wake of a rotor

Journal of Physics Conference Series ◽

10.1088/1742-6596/1934/1/012007 ◽

2021 ◽

Vol 1934 (1) ◽

pp. 012007

Author(s):

D Schröder ◽

T Leweke ◽

R Hörnschemeyer ◽

E Stumpf

Keyword(s):

Vortex Pair ◽

Helical Vortex

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Rates, pathways, and end states of nonlinear evolution in decaying two‐dimensional turbulence: Scaling theory versus selective decay

Physics of Fluids A Fluid Dynamics ◽

10.1063/1.858251 ◽

1992 ◽

Vol 4 (6) ◽

pp. 1314-1316 ◽

Cited By ~ 53

Author(s):

G. F. Carnevale ◽

J. C. McWilliams ◽

Y. Pomeau ◽

J. B. Weiss ◽

W. R. Young

Keyword(s):

Nonlinear Evolution ◽

Scaling Theory ◽

Two Dimensional ◽

Theory Versus ◽

Selective Decay ◽

Turbulence Scaling

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The approach of a vortex pair to a plane surface in inviscid fluid

Journal of Fluid Mechanics ◽

10.1017/s0022112079000744 ◽

1979 ◽

Vol 92 (3) ◽

pp. 497-503 ◽

Cited By ~ 55

Author(s):

P. G. Saffman

Keyword(s):

Approximate Calculation ◽

Plane Surface ◽

Vortex Pair ◽

Plane Wall ◽

Inviscid Fluid ◽

Viscous Effects ◽

Axis Ratio ◽

Local Rate

It is shown that a symmetrical vortex pair consisting of equal and opposite vortices approaching a plane wall at right angles must approach the wall monotonically in the absence of viscous effects. An approximate calculation is carried out for uniform vortices in which the vortices are assumed to be deformed into ellipses whose axis ratio is determined by the local rate of strain according to the results of Moore & Saffman (1971).

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Steady longitudinal vortices in supersonic turbulent separated flows

Journal of Fluid Mechanics ◽

10.1017/s0022112010006105 ◽

2011 ◽

Vol 672 ◽

pp. 451-476 ◽

Cited By ~ 14

Author(s):

ERICH SCHÜLEIN ◽

VICTOR M. TROFIMOV

Keyword(s):

High Speed ◽

Large Scale ◽

Roughness Element ◽

Vortex Generator ◽

Vortex Pair ◽

Leading Edge ◽

Separated Flows ◽

Vortex Generators ◽

Longitudinal Vortices ◽

Oil Flow

Large-scale longitudinal vortices in high-speed turbulent separated flows caused by relatively small irregularities at the model leading edges or at the model surfaces are investigated in this paper. Oil-flow visualization and infrared thermography techniques were applied in the wind tunnel tests at Mach numbers 3 and 5 to investigate the nominally 2-D ramp flow at deflection angles of 20°, 25° and 30°. The surface contour anomalies have been artificially simulated by very thin strips (vortex generators) of different shapes and thicknesses attached to the model surface. It is shown that the introduced streamwise vortical disturbances survive over very large downstream distances of the order of 104 vortex-generator heights in turbulent supersonic flows without pressure gradients. It is demonstrated that each vortex pair induced in the reattachment region of the ramp is definitely a child of a vortex pair, which was generated originally, for instance, by the small roughness element near the leading edge. The dependence of the spacing and intensity of the observed longitudinal vortices on the introduced disturbances (thickness and spanwise size of vortex generators) and on the flow parameters (Reynolds numbers, boundary-layer thickness, compression corner angles, etc.) has been shown experimentally.

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