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Roughness Induced Transition in a Supersonic Boundary LayerDirect numerical simulation is used to investigate the transition induced by threedimensional isolated roughness elements in a supersonic boundary layer at a free stream Mach number of 3.5. Simulations are performed for two different configurations: one is a square planform roughness and the other is a diamond planform roughness. The mean-flow calculations show that the roughness induces counter rotating streamwise vortices downstream of the roughness. These vortices persist for a long distance downstream and lift the low momentum fluid from the near wall region and place it near the outer part of the boundary layer. This forms highly inflectional boundary layer profiles. These observations agree with recent experimental observations. The receptivity calculations showed that the amplitudes of the mass-flux fluctuations near the neutral point for the diamond shape roughness are the same as the amplitude of the acoustic disturbances. They are three times smaller for the square shape roughness.
Document ID
20140000468
Acquisition Source
Langley Research Center
Document Type
Conference Paper
External Source(s)
doi:10.2514/6.2013-3105
Authors
Balakumar, Ponnampalam (NASA Langley Research Center Hampton, VA, United States)
Kergerise, Michael A. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
January 29, 2014
Publication Date
June 24, 2013
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
NF1675L-15687
Meeting Information
Meeting: AIAA Fluid Dynamics Conference and Exhibit
Location: San Diego, CA
Country: United States
Start Date: June 24, 2013
End Date: June 27, 2013
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 794072.02.07.02.01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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