Accession Number : AD0642298

Title :   LARGE EDDY STRUCTURE OF A TURBULENT WAKE.

Descriptive Note : Doctoral thesis,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF AEROSPACE ENGINEERING

Personal Author(s) : Payne,Fred R.

Report Date : SEP 1966

Pagination or Media Count : 180

Abstract : Lumley's objective definition of the intuitive concept of 'large eddy' leads to an eigenvalue problem. In this report, the first few eigenfunctions are determined for velocity correlations measured in the turbulent wake of a circular cylinder; these are interpreted in terms of the associated representation theorems. The eigenvalue problem was solved in Fourier space and the most energetic eigenfunction was transformed to 'real space.' This mode is a vortex pair approximately normal to the plane of the wake; its planes of circulation are normal to the direction of positive maximum mean strain rate. The structure is qualitatively similar to Grant's intuitive model based on the same data. Lumley's interpretation of the most energetic modes as the large eddies is verified as correct. However, the strong non-linearity of the dynamics of these eddies (suggested by the apparent dominance of vortex stretching) combined with the slow decay of eigenvalues with increasing order, implies that analytic solution of the equations of motion for these eddies will be a formidable problem. (Author)

Descriptors :   (*WAKE, *FLUID DYNAMICS), (*TURBULENCE, WAKE), MATHEMATICAL MODELS, FUNCTIONAL ANALYSIS, CURVE FITTING, MATRICES(MATHEMATICS), INTEGRAL TRANSFORMS

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE