Accession Number : ADA300048

Title :   The Influence of Convection Velocity on the Turbulent Wall Pressure Wavenumber-Frequency Spectrum.

Descriptive Note : Final rept.,

Corporate Author : NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI

Personal Author(s) : Keith, William L. ; Abraham, Bruce M.

PDF Url : ADA300048

Report Date : 21 APR 1995

Pagination or Media Count : 29

Abstract : Cross spectral and cross correlation data from experiments and numerical simulations have shown the turbulent wall pressure convection velocity to vary with the streamwise spatial separation, xi, due to the spatial decay rates of turbulent structures in the inner and outer regions of the boundary layer. This effect is shown to have a significant impact on the distribution of energy in the wavenumber-frequency spectrum Phi(k1, omega). The overprediction of spectral levels at low wavenumbers using the standard Corcos model is shown to result from assuming a constant convection velocity in the cross spectrum. The spectral levels at subconvective and lower wavenumbers are shown to be directly influenced by the decay and convection of turbulence in both the inner and outer regions of the boundary layer. These results compare favorably with recent numerical results. The attenuations in the autospectrum due to finite diameter sensors are shown not to be significantly influenced by this effect. Convection velocity measurements from past investigations that cover the range 285 <or= R sub Theta <or= 29,000 are compared, and an outer variable scaling is found to be the most effective for collapsing the data. (MM)

Descriptors :   *CONVECTION, *TURBULENT BOUNDARY LAYER, *BOUNDARY LAYER FLOW, VELOCITY, SPATIAL DISTRIBUTION, DETECTORS, NUMERICAL ANALYSIS, TURBULENCE, SPECTRA, SCALING FACTOR, PRESSURE, WALLS, FLOW SEPARATION, CROSS CORRELATION.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE