Measurements of the Correlation between the Fluctuating Velocities and the Fluctuating Wall Pressure in a Thick Turbulent Boundary Layer

Abstract

Turbulent motion in a thick (5-inch) boundary layer with zero longitudinal pressure gradient which is produced by natural transition on a smooth surface was studied. Measurements were made of the space-time correlation between the fluctuating wall pressure and the fluctuating velocities in the layer, and between the fluctuating wall pressure and the time derivative of the fluctuating velocity normal to the wall. At any height in the boundary layer, the velocity disturbance which was correlated with the wall pressure disturbances was convected at the local mean speed. The correlation of the wall pressure with the longitudinal velocity was opposite in sign to the correlation of the wall pressure with the velocity normal to the wall. This implied that the part of the velocity field which is correlated with the wall pressure also produces turbulent shear. The approximate structure of the pressure velocity correlation was obtained from measurements of the space-time correlation between the wall pressure and the fluctuating velocity at various points in the layer, Isocorrelation contours with zero time delay were mapped in three orthogonal planes parallel and perpendicular to the wall. The structure of the isocorrelation contours suggests that the wall pressure is produced by a hierarchy of endies which produce turbulent shear and have a greater extent in the stream direction than normal to the stream. In planes parallel to the wall, the contours of the correlation between the wall pressure and velocity normal to the wall exhibit a definite swept-back structure. Farther from the wall, the swept-back structure disappears and the isocorrelation contours are symmetric about a line parallel to the wall and normal to the stream.

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Document Details

Document Type
Technical Report
Publication Date
Apr 01, 1963
Accession Number
AD0436675

Entities

People

  • C. E. Wooldridge
  • W. W. Willmarth

Organizations

  • AGARD

Tags

DTIC Thesaurus Topics

  • Boundary Layer
  • Computational Fluid Dynamics
  • Convection
  • Flow Visualization
  • Fluid Dynamics
  • Fluid Mechanics
  • Frequency Bands
  • Measurement
  • Military Research
  • National Security
  • Physics Laboratories
  • Power Spectra
  • Pressure Transducers
  • Reynolds Number
  • Shear Flow
  • Stratified Fluids
  • Wind Tunnels

Fields of Study

  • Physics

Readers

  • Fluid Mechanics and Fluid Dynamics.

Technology Areas

  • Space
  • Space - Hall-Effect Thruster