Accession Number:

ADA179720

Title:

Experimental and Numerical Investigation of Coherent Structures in Turbulent Wake Flows.

Descriptive Note:

Annual rept. 5 Feb 86-4 Feb 87,

Corporate Author:

ARIZONA UNIV TUCSON ENGINEERING EXPERIMENT STATION

Personal Author(s):

Report Date:

1987-04-07

Pagination or Media Count:

19.0

Abstract:

Recent x wire measurements in a plane turbulent wake are presented. Sinuous disturbances at several amplitudes and frequencies were introduced to the wake by oscillating a small trailing edge flap. The Strouhal numbers of the perturbations were specially chosen so that the downstream location of the neutral point where the spatial amplification rate obtained from linear stability theory vanishes was well within the range of measurements. The stream wise variation of the half width of the wake and the centerline velocity deficit was dependent on the amplitude level and showed dramatic deviations at large forcing levels from the well-known square root behavior of the unforced case. The measured coherent Reynolds stressed were observed to change sign in the neighborhood of the location of the neutral point as predicted by linear viscous theory. The numerical simulations of free shear layers and progress towards the wake simulations are also discussed.

Subject Categories:

  • Aerodynamics
  • Numerical Mathematics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE