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Turbulence effect on crossflow around a circular cylinder at subcritical Reynolds numbersAn investigation of the effect of freestream turbulence on the flow around a smooth circular cylinder at subcritical Reynolds numbers from 5.2 x 10 to the 4th power to 2.09 x 10 to the 5th power was conducted. Measurements show that the interaction of incident turbulence with the initial laminar boundary layer: (1) modifies the characteristics of the mean surface pressure distribution; (2) induces an aft shift in the separation point ranging from 5 to 50 beyond the laminar separation angle of 80 degrees; and, (3) reduces the mean drag coefficient to values between 97 and 46% of its nearly constant laminar counterpart. The extent of these changes depends on the particular Reynolds number background turbulence combination. These results demonstrate that a boundary-layer flow similar to that found in critical, supercritical and/or transcritical flow regimes is induced by turbulence at subcritical Reynolds numbers and, hence, the effect of turbulence is equivalent to an effective increase in the Reynolds number. The change in the nature and properties of the boundary layer in the subcritical regime, consequent upon the penetration of turbulence into it, is in agreement with the model proposed by the vorticity-amplification theory.
Document ID
19830005116
Document Type
Contractor Report (CR)
Authors
Sadeh, W. Z.
(Colorado State Univ. Fort Collins, CO, United States)
Saharon, D. B.
(Colorado State Univ. Fort Collins, CO, United States)
Date Acquired
September 4, 2013
Publication Date
November 1, 1982
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
NASA-CR-3622
CER-81-82-WZS-DBS51
NAS 1.26:3622
Funding Number(s)
CONTRACT_GRANT: NSG-3127
PROJECT: RTOP 505-36-12
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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