Accession Number:

ADA285622

Title:

Computational Studies of Laminar to Turbulence Transition

Descriptive Note:

Final rept. 15 Dec 1990-14 May 1994

Corporate Author:

HIGH TECHNOLOGY CORP HAMPTON VA

Personal Author(s):

Report Date:

1994-07-14

Pagination or Media Count:

133.0

Abstract:

Nonlinear evolution of Goertler and crossflow vortices is investigated. The associated secondary instabilities of these streamwise vortices are also studied. The Goertler vortex is found to be subject to two types of secondary modes a sinuous mode and a varicose mode similar to that observed in the experiments. The growth rate of the sinuous mode is higher initially but the varicose mode becomes more unstable in the downstream. It is also found that crossflow vortices are subject to a high frequency secondary instability prior to breakdown, as found in experiments performed on swept wings. In agreement with the experiments, our calculations show that the frequency of this secondary instability, which resides on top of the crossflow vortex, is an order of magnitude higher than the frequency of the most amplified traveling crossflow disturbances. The interaction of stationary and traveling disturbances is also considered. These studies have been carried out by using parabolized stability equations PSE and a two-dimensional 2D eigenvalue approach. The mathematical nature of PSE approximation is also discussed. Goertler vortices, Crossflow vortices, Secondary instability, Parabolized stability equations, 2D Eigenvalue problem.

Subject Categories:

  • Numerical Mathematics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE