Evolution of a Vortical Structure Associated with the Bursting Event in a Channel Flow
The temporal evolution of a horseshoe vortex structure in a ehannel is investigated by a numerical simulation. A spectral numerical method is employed to integrate the time-dependent, three-dimensional Navier-Stokes equations. The initial vortical structure is obtained by applying a conditional sampling technique to a data base generated from a direct simulation of a turbulent channel flow. The evolution of this vortical structure under the influence of the self-induced motion and the mean shear is presented. It is shown that the initial sheet-like vortical structure rolls up into a vortex tube as it is convected downstream. Turbulence characteristics associated with the vortex are investigated. Production of vortic-ity due to vortex stretching is high inside the vortex legs, although it is also substantial in the tip region and above the legs. High Reynolds shear stress is produced near the tip of the vortex.
KeywordsVortex Ring Vortical Structure Vortex Line Reynolds Shear Stress Vortex Tube
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