A numerical study of vortex interaction

1984 ◽  
Vol 146 ◽  
pp. 331-345 ◽  
Author(s):  
I. G. Bromilow ◽  
R. R. Clements
Keyword(s):  
Flow Visualization ◽  
Numerical Study ◽  
Experimental Studies ◽  
Shear Layers ◽  
Controlled Study ◽  
Vortex Interaction ◽  
Flow Conditions ◽  
Discrete Vortex ◽  
Vortex Model ◽  
Discrete Vortex Model

Flow visualization has shown that the interaction of line vortices is a combination of tearing, elongation and rotation, the extent of each depending upon the flow conditions. A discrete-vortex model is used to study the interaction of two and three growing line vortices of different strengths and to assess the suitability of the method for such simulation.Many of the features observed in experimental studies of shear layers are reproduced. The controlled study shows the importance and rapidity of the tearing process under certain conditions.

scholarly journals Vortices on Sound Generation and Dissipation in Musical Flue Instruments

2020 ◽  
Author(s):  
Shigeru Yoshikawa
Keyword(s):  
Acoustic Energy ◽  
Layer Model ◽  
Pipe Organ ◽  
Discrete Vortex ◽  
Vortex Sound ◽  
Vortex Model ◽  
Vortex Layer ◽  
Sound Theory ◽  
Drive Model ◽  
Discrete Vortex Model

Musical flue instruments such as the pipe organ and flute mainly consist of the acoustic pipe resonance and the jet impinging against the pipe edge. The edge tone is used to be considered as the energy source coupling to the pipe resonance. However, jet-drive models describing the complex jet/pipe interaction were proposed in the late 1960s. Such models were more developed and then improved to the discrete-vortex model and vortex-layer model by introducing fluid-dynamical viewpoint, particularly vortex sound theory on acoustic energy generation and dissipation. Generally, the discrete-vortex model is well applied to thick jets, while the jet-drive model and the vortex-layer model are valid to thin jets used in most flue instruments. The acoustically induced vortex (acoustic vortex) is observed near the amplitude saturation with the aid of flow visualization and is regarded as the final sound dissipation agent. On the other hand, vortex layers consisting of very small vortices along both sides of the jet are visualized by the phase-locked PIV and considered to generate the acceleration unbalance between both vortex layers that induces the jet wavy motion coupled with the pipe resonance. Vortices from the jet visualized by direct numerical simulations are briefly discussed.

Discrete-vortex simulation of a turbulent separation bubble

1982 ◽  
Vol 120 ◽  
pp. 219-244 ◽  
Author(s):  
Masaru Kiya ◽  
Kyuro Sasaki ◽  
Mikio Arie
Keyword(s):  
Surface Pressure ◽  
Solid Surface ◽  
Separation Bubble ◽  
Simple Procedure ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Vortex Filaments ◽  
Discrete Vortex ◽  
Vortex Model ◽  
Discrete Vortex Model

The discrete-vortex model is applied to simulate the separation bubble over a two- dimensional blunt flat plate with finite thickness and right-angled corners, which is aligned parallel to a uniform approaching stream. This flow situation is chosen because, unlike most previous applications of the model, the separation bubble is supposed to be strongly affected by a nearby solid surface. The major objective of this paper is to examine to what extent the discrete-vortex model is effective for such a flow. A simple procedure is employed to represent the effect of viscosity near the solid surface; in particular, the no-slip condition on the solid surface. A reduction in the circulation of elemental vortices is introduced as a function of their ages in order to represent the three-dimensional deformation of vortex filaments, An experiment was also performed for comparison purposes.The calculation yielded reasonable predictions of the time-mean and r.m.s. values of the velocity and the surface-pressure fluctuations, together with correlations between their fluctuating components, over most of the separation bubble. The interrelation between instantaneous spatial variations of the surface-pressure and velocity fluctuations were also obtained. A comparison between the calculated and measured results suggests that, in the real flow, the three-dimensional deformation of vortex filaments will become more and more dominant as the reattachment point is approached.

Discrete Vortex Model of Jet‐Forced Flow in Circular Reservoir

1988 ◽  
Vol 114 (3) ◽  
pp. 283-298 ◽  
Author(s):  
A. G. L. Borthwick ◽  
J. R. Chaplin ◽  
K. H. M. Ali
Keyword(s):  
Forced Flow ◽  
Discrete Vortex ◽  
Vortex Model ◽  
Discrete Vortex Model

Impulsively Started Steady Flow About Rectangular Prisms: Experiments and Discrete Vortex Analysis

1986 ◽  
Vol 108 (1) ◽  
pp. 47-54 ◽  
Author(s):  
T. Sarpkaya ◽  
C. J. Ihrig
Keyword(s):  
Reynolds Number ◽  
Steady Flow ◽  
Strouhal Number ◽  
Relative Displacement ◽  
Shear Layers ◽  
Discrete Vortex ◽  
Vortex Model ◽  
Vorticity Distribution ◽  
Initial Rise ◽  
Lift And Drag

Impulsively started steady flow about sharp-edged rectangular prisms has been investigated experimentally and numerically. The forces acting on the bodies have been determined at a Reynolds number of about 20,000 for various angles of incidence as a function of the relative displacement of the fluid. The results have shown that the shedding of the first few vortices has profound effects on both the lift and drag coefficients, often resulting in a large initial rise in drag. The surface-vorticity-distribution version of the discrete vortex model has shown that the strength of the vortex clusters varies from 80 to 90 percent of the vorticity generated in the shear layers. The Strouhal number is correctly predicted but the calculated forces are somewhat larger than those measured experimentally.

Calculation of asymmetric vortex separation on cones and tangent ogives based on a discrete vortex model

AIAA Journal ◽  
1989 ◽  
Vol 27 (12) ◽  
pp. 1824-1826 ◽  
Author(s):  
Suei Chin ◽  
C. Edward Lan ◽  
Thomas G. Gainer
Keyword(s):  
Discrete Vortex ◽  
Asymmetric Vortex ◽  
Vortex Model ◽  
Vortex Separation ◽  
Discrete Vortex Model
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