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Streaming vorticity flux from oscillating walls with finite amplitudeHow to describe vorticity creation from a moving wall is a long standing problem. This paper discusses relevant issues at the fundamental level. First, it is shown that the concept of 'vorticity flux due to wall acceleration' can be best understood by following fluid particles on the wall rather than observing the flow at fixed spatial points. This is of crucial importance when the time-averaged flux is to be considered. The averaged flux has to be estimated in a wall-fixed frame of reference (in which there is no flux due to wall acceleration at all); or, if an inertial frame of reference is used, the generalized Lagrangian mean (GLM) also gives the same result. Then, for some simple but typical configurations, the time-averaged vorticity flux from a harmonically oscillating wall with finite amplitude is analyzed, without appealing to small perturbation. The main conclusion is that the wall oscillation will produce an additional mean vorticity flux (a fully nonlinear streaming effect), which is partially responsible for the mechanism of vortex flow control by waves. The results provide qualitative explanation for some experimentally and/or computationally observed phenomena.
Document ID
19930068520
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Wu, J. Z. (NASA Langley Research Center Hampton, VA, United States)
Wu, X. H. (NASA Langley Research Center Hampton, VA, United States)
Wu, J. M. (Tennessee Univ. Tullahoma, United States)
Date Acquired
August 16, 2013
Publication Date
August 1, 1993
Publication Information
Publication: Physics of Fluids A
Volume: 5
Issue: 8
ISSN: 0899-8213
Subject Category
FLUID MECHANICS AND HEAT TRANSFER
Funding Number(s)
CONTRACT_GRANT: NAG1-844
Distribution Limits
Public
Copyright
Other