Accession Number : ADA307878

Title :   Direct Numerical Simulation of a Temporally Evolving Incompressible Plane Wake: Effect of Initial Conditions on Evolution and Topology.

Descriptive Note : Final rept.,

Corporate Author : WRIGHT LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Sondergaard, Rolf

PDF Url : ADA307878

Report Date : MAR 1996

Pagination or Media Count : 326

Abstract : Direct numerical simulations have been used to examine the effect of the initial disturbance field on the development of three dimensionality and the transition to turbulence in the incompressible plane wake. Initial disturbances fields examined were combinations of two dimensional waves and symmetric pairs of 60 oblique waves at the fundamental, subharmonic, and subharmonic wavelengths. Results indicate that the presence of 60 disturbances at the subharmonic streamwise wavelength results in the development of strong coherent three dimensional structures. The resulting strong three dimensional rate of strain triggers the growth of intense fine scale motions. Wakes initiated with 60 deg disturbances at the fundamental streamwise wavelength develop weak coherent streamwise structures, and do not develop significant fine scale motions, even at high Reynolds numbers. The wakes which develop strong three-dimensional structures exhibit growth rates on par with experimentally observed turbulent plane wakes. Wakes which develop only weak three dimensional structures exhibit significantly lower late time growth rates.

Descriptors :   *TURBULENCE, *WAKE, NUMERICAL ANALYSIS, COHERENCE, INTENSITY, TOPOLOGY, SCALE, TRANSITIONS, LOW STRENGTH, PLANE WAVES, REYNOLDS NUMBER, INCOMPRESSIBLE FLOW, DIGITAL SIMULATION, THREE DIMENSIONAL FLOW.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE