Dynamics of Large Scale Structures in Turbulent Two Dimensional Wakes

1991 ◽  
pp. 33-49 ◽  
Author(s):  
D. G. Christakis ◽  
D. D. Papailiou
Keyword(s):  
Large Scale ◽  
Two Dimensional ◽  
Large Scale Structures ◽  
Scale Structures

Direct numerical simulation of a three-dimensional temporal mixing layer with particle dispersion

1998 ◽  
Vol 358 ◽  
pp. 61-85 ◽  
Author(s):  
WEI LING ◽  
J. N. CHUNG ◽  
T. R. TROUTT ◽  
C. T. CROWE
Keyword(s):  
Large Scale ◽  
Initial Perturbation ◽  
Mixing Layer ◽  
Three Dimensional ◽  
Particle Dispersion ◽  
Spanwise Direction ◽  
Two Dimensional ◽  
Streamwise Direction ◽  
Large Scale Structures ◽  
Scale Structures

The three-dimensional mixing layer is characterized by both two-dimensional and streamwise large-scale structures. Understanding the effects of those large-scale structures on the dispersion of particles is very important. Using a pseudospectral method, the large-scale structures of a three-dimensional temporally developing mixing layer and the associated dispersion patterns of particles were simulated. The Fourier expansion was used for spatial derivatives due to the periodic boundary conditions in the streamwise and the spanwise directions and the free-slip boundary condition in the transverse direction. A second-order Adam–Bashforth scheme was used in the time integration. Both a two-dimensional perturbation, which was based on the unstable wavenumbers of the streamwise direction, and a three-dimensional perturbation, derived from an isotropic energy spectrum, were imposed initially. Particles with different Stokes numbers were traced by the Lagrangian approach based on one-way coupling between the continuous and the dispersed phases.The time scale and length scale for the pairing were found to be twice those for the rollup. The streamwise large-scale structures develop from the initial perturbation and the most unstable wavelength in the spanwise direction was found to be about two thirds of that in the streamwise direction. The pairing of the spanwise vortices was also found to have a suppressing effect on the development of the three-dimensionality. Particles with Stokes number of the order of unity were found to have the largest concentration on the circumference of the two-dimensional large-scale structures. The presence of the streamwise large-scale structures causes the variation of the particle concentrations along the spanwise and the transverse directions. The extent of variation also increases with the development of the three-dimensionality, which results in the ‘mushroom’ shape of the particle distribution.

On the large-scale structures in two-dimensional, small-deficit, turbulent wakes

1986 ◽  
Vol 168 (-1) ◽  
pp. 31 ◽  
Author(s):  
I. Wygnanski ◽  
F. Champagne ◽  
B. Marasli
Keyword(s):  
Large Scale ◽  
Two Dimensional ◽  
Large Scale Structures ◽  
Turbulent Wakes ◽  
Scale Structures

scholarly journals The effect of small-scale forcing on large-scale structures in two-dimensional flows

1996 ◽  
Vol 98 (2-4) ◽  
pp. 321-334 ◽  
Author(s):  
Alexei Chekhlov ◽  
Steven A. Orszag ◽  
Semion Sukoriansky ◽  
Boris Galperin ◽  
Ilya Staroselsky
Keyword(s):  
Large Scale ◽  
Small Scale ◽  
Two Dimensional ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Two Dimensional Flows

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

Large-Scale Structures in a Compressible Mixing Layer over a Cavity

AIAA Journal ◽  
2003 ◽  
Vol 41 (12) ◽  
Author(s):  
Jonathan Poggie ◽  
Alexander J. Smits
Keyword(s):  
Large Scale ◽  
Mixing Layer ◽  
Compressible Mixing Layer ◽  
Large Scale Structures ◽  
Scale Structures
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