Accession Number:

ADA179247

Title:

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

Descriptive Note:

Annual rept. Feb 85-Feb 86,

Corporate Author:

VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIENCE AND MECHANICS

Personal Author(s):

Report Date:

1986-12-01

Pagination or Media Count:

12.0

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 are currently applied to shed more light on this nonlinear process. Keywords Boundary, Transition.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE