NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Nonlinear Transient Growth and Boundary Layer TransitionParabolized stability equations (PSE) are used in a variational approach to study the optimal, non-modal disturbance growth in a Mach 3 at plate boundary layer and a Mach 6 circular cone boundary layer. As noted in previous works, the optimal initial disturbances correspond to steady counter-rotating streamwise vortices, which subsequently lead to the formation of streamwise-elongated structures, i.e., streaks, via a lift-up effect. The nonlinear evolution of the linearly optimal stationary perturbations is computed using the nonlinear plane-marching PSE for stationary perturbations. A fully implicit marching technique is used to facilitate the computation of nonlinear streaks with large amplitudes. To assess the effect of the finite-amplitude streaks on transition, the linear form of plane- marching PSE is used to investigate the instability of the boundary layer flow modified by spanwise periodic streaks. The onset of bypass transition is estimated by using an N- factor criterion based on the amplification of the streak instabilities. Results show that, for both flow configurations of interest, streaks of sufficiently large amplitude can lead to significantly earlier onset of transition than that in an unperturbed boundary layer without any streaks.
Document ID
20160010024
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Pedro Paredes ORCID
(Langley Research Center Hampton, Virginia, United States)
Meelan M Choudhari ORCID
(Langley Research Center Hampton, Virginia, United States)
Fei Li
(Langley Research Center Hampton, Virginia, United States)
Date Acquired
August 4, 2016
Publication Date
June 10, 2016
Publication Information
Publication: 46th AIAA Fluid Dynamics Conference
Publisher: American Institute of Aeronautics and Astronautics
e-ISBN: 9781624104367
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
NF1676L-22755
AIAA 2016-3956
Meeting Information
Meeting: 46th AIAA Fluid Dynamics Conference
Location: Washington, DC
Country: US
Start Date: June 13, 2016
End Date: June 17, 2016
Sponsors: American Institute of Aeronautics and Astronautics
Funding Number(s)
WBS: 109492.02.07.01.01.02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Laminar turbulent transition
Parabolized stability equations
Vortices
Incompressible flow
Freestream Mach number
Direct numerical simulation
Surface roughness
Shape functions
Hydrodynamic instability
Compressibility effect
No Preview Available