Accession Number : ADA327709

Title :   Three-Dimensional Correlation and Spectral Functions for Turbulent Velocities in Homogeneous and Surface-Blocked Boundary Layers.

Descriptive Note : Final rept. 1 Feb-30 Apr 96,

Corporate Author : ARMY RESEARCH LAB ADELPHI MD

Personal Author(s) : Wilson, David K.

PDF Url : ADA327709

Report Date : JUL 1997

Pagination or Media Count : 48

Abstract : A pair of three-dimensional (3D) models for correlation functions and spectra of velocity fluctuations in turbulent boundary layers is presented. First, the case of homogeneous turbulence is considered. Von Karman's energy spectrum is used to develop a complete set of 3D correlation and spectral equations. Second, it is shown how the homogeneous spectra can be modified to include the effect of eddy-blocking at the ground. Assuming that the disturbance to the turbulent flow resulting from the blocking is irrotational, an equation is developed that allows one to write the vertically inhomogeneous, 2D cross spectra as a function of the 2D cross spectra for a homogeneous flow. Although there are only two adjustable parameters in the inhomogeneous model, the variance and a length scale, the model is shown to agree quite well with a variety of previous results for the atmospheric convective boundary layer (CBL).

Descriptors :   *ATMOSPHERIC MOTION, *TURBULENT BOUNDARY LAYER, VELOCITY, TWO DIMENSIONAL, CONVECTION, TURBULENT FLOW, THREE DIMENSIONAL, SPECTRA, SCALE, REYNOLDS NUMBER, FUNCTIONS(MATHEMATICS), HOMOGENEITY.

Subject Categories : Atmospheric Physics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE