Temporal and Spatial Growth of Subharmonic Disturbances in Falkner-Skan Flows
Abstract
Careful experiments on boundary layer transition conducted in low turbulence wind tunnels have resolved three stages in the breakdown of laminar flow into turbulence: in the first stage, two-dimensional oscillations, commonly referred to as TS waves, appear and propagate in the direction of the flow; in the second stage there appears a rapid three-dimensional deformation of the oscillatory flow; and in the brief third stage high frequency, small scale, quasi-random fluctuations appear and quickly lead the flow into turbulence. The recent analysis of the second stage based on a secondary instability mechanism arising from a parametric resonance induced by the TS wave has given results in quantitative agreement with experimental observations. Using this approach, Herbert had studied the phenomenon in plane channel flow and in a Blasius boundary layer. This thesis studies the effect of pressure gradients on the behavior of secondary instabilities, by extending Herbert's analysis to the Falkner-Skan family of profiles, and develops a spatial formulation for disturbance growth to exactly match the experimentally observed behavior. Keywords: governing equations; numerical methods and procedures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1985
- Accession Number
- ADA163512
Entities
People
- Fabio P. Bertolotti
Organizations
- Virginia Tech