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Initiation of Turbulent Spots in a Laminar Boundary Layer by Rigid Falling ParticulatesA transitional laminar boundary layer is developed on a 1m wide km long flat plate in a 0.6m deep water channel with a freestream velocity of 15-50 cm/s. A particulate dispenser under computer control ejects individual particles having diameters of 1/3 delta into the free stream. The particulates are introduced with an initial velocity of U(sub infinity) in the direction of the free stream. They have differing specific gravities of 1.03-2.7 which introduces an additional non-dimensional parameter relating the time taken to traverse the boundary layer to the convective time scale. The particulates produce a wake in the upper region of the boundary layer as they sink towards the wall. Visualization data taken over the range 5 x 10(exp 4) less than Re(sub x) less than 5 x 10(exp 5) indicate that turbulent spots are produced by the disturbances due to the wake rather than by the particulates themselves. This suggests that the spot formation process in this case may be inviscid in nature and may not be strongly influenced by the presence of the wall.
Document ID
20070038951
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Blackwelder, R. F. (University of Southern California Los Angeles, CA, United States)
Browand, F. K. (University of Southern California Los Angeles, CA, United States)
Fisher, C. (University of Southern California Los Angeles, CA, United States)
Tanaguichi, P. (University of Southern California Los Angeles, CA, United States)
Date Acquired
August 24, 2013
Publication Date
March 1, 2007
Publication Information
Publication: Minnowbrook I: 1993 Workshop on End-Stage Boundary Layer Transition
Subject Category
Aerodynamics
Distribution Limits
Public
Copyright
Public Use Permitted.

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IDRelationTitle20070038942Collected WorksMinnowbrook I: 1993 Workshop on End-Stage Boundary Layer Transition
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