Accession Number : ADA211282

Title :   Questions from the Willmarth Workshop on New Directions in Research on Turbulent Wall-Layer Structures.

Descriptive Note : Final rept.,

Corporate Author : TEXAS UNIV AT AUSTIN DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Blackwelder, R. F. ; Panton, R. L. ; Wallace, J. M.

Report Date : AUG 1989

Pagination or Media Count : 7

Abstract : Certain patterns of motion are observed to occur repeatedly in turbulence. The search to identify these events, determine their interrelationships, and establish their importance is known as Structure Research. Important improvements have been seen in both experimental instrumentation and in the direct numerical simulation of turbulent flows with computers. Does the bursting process associate with a single, monolithic, eddy structure made up of many associated structure elements or is it composed of many smaller relatively independent structure elements? How are the low speed streaks and temporally related to Reynolds stress producing elements (such as ejections and sweeps) and to the wall stress? Experiments and numerical simulations reveal that there are frequently intense internal shear layers (in both the normal and span directions) in the near wall region. What are the sources and significance of these shear layers? Are the structure elements observed in wall layers part of a vortex structure, if so of what type? How can knowledge of vortex dynamics be applied to understanding the origin, evolution, and dynamics of these structures? What are the effects of Reynolds number on the structure elements and their characteristics? What are the effects of parameters such as wall-roughness, pressure-gradients, surface-curvature, and three-dimensionality on the structure elements? How do the evolutionary histories of structures change with the above parameters? (jhd)

Descriptors :   *EDDY CURRENTS, *TURBULENCE, COMPUTER APPLICATIONS, DYNAMICS, DIGITAL SIMULATION, FLOW FIELDS, INSTRUMENTATION, INTENSITY, INTERNAL, LAYERS, LOW VELOCITY, MATHEMATICAL MODELS, MOMENTUM TRANSFER, MOTION, NUMERICAL ANALYSIS, PATTERNS, REGIONS, REYNOLDS NUMBER, RUPTURE, SHEAR PROPERTIES, STRESSES, STRUCTURAL COMPONENTS, STRUCTURES, TURBULENT FLOW, VORTICES, WALLS, WORKSHOPS.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE