Accession Number : ADA185466

Title :   Three-Dimensional Structure of Boundary Layers in Transition to Turbulence.

Descriptive Note : Final rept. 1 Feb 84-28 Feb 87,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIE NCE AND MECHANICS

Personal Author(s) : Herbert, Thorwald

PDF Url : ADA185466

Report Date : 24 Jun 1987

Pagination or Media Count : 78

Abstract : A unified theory of secondary instability in wall-bound shear flows has been developed. This theory rests on Floquet systems of stability equations and permits classification and quantitative analysis of different modes of secondary instability in the three-dimensional stage of laminar-turbulent transition. The catalogue of solutions is consistent with observations and predicts other phenomena that have not been identified in experiments. The theoretical results have been used to reproduce patterns in flow visualizations by computer animation. Analysis of the energy balance has shown a feedback loop between mean flow, two-dimensional, and three-dimensional disturbances that is considered key to the process of self-sustained transition. Various techniques have been developed to investigate details of the nonlinear three-dimensional processes involved in this feedback loop. Keywords: Boundary layer, Stability, Transition.

Descriptors :   *BOUNDARY LAYER FLOW, *BOUNDARY LAYER TRANSITION, BALANCE, BOUNDARY LAYER, CATALOGS, ENERGY, EQUATIONS, FEEDBACK, FLOW, FLOW VISUALIZATION, LAMINAR FLOW, LOOPS, MEAN, NONLINEAR SYSTEMS, QUANTITATIVE ANALYSIS, SECONDARY, SOLUTIONS(GENERAL), STABILITY, STRUCTURES, THEORY, THREE DIMENSIONAL, TRANSITIONS, TURBULENCE, TURBULENT FLOW, STRUCTURAL PROPERTIES, WALLS, TWO DIMENSIONAL FLOW, SHEAR PROPERTIES, COMPUTER GRAPHICS, THREE DIMENSIONAL FLOW

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE