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An experimental search for near-wall boundary conditions for large eddy simulationInstantaneous wall shear stress and streamwise velocities have been measured simultaneously in a flat plate, turbulent boundary layer at moderate Reynolds number in an effort to provide experimental support for large eddy simulations. Data were obtained by using a buried-wire wall shear gage and a hot-wire rake positioned in the log region of the flow. All data processing was accomplished with digital data analysis techniques on a minicomputer. Fluctuations of the instantaneous U plus versus Y plus profiles about a mean law of the wall are shown to be significant and complex. Peak cross-correlation values between wall shear stress and the velocities are high and reflect the passage of a large structure inclined at a small angle to the wall. Estimates of this angle are consistent with those made by other investigators. Conditional sampling techniques were used to detect the passage of various sizes and types of flow disturbances (events) and to estimate their mean frequency of occurrence. Events characterized by large and sudden streamwise accelerations were found to be highly coherent throughout the log region and were strongly correlated with large fluctuations in wall shear-stress. Phase randomness between the near-wall quantities and the outer velocities was small. The results suggest that the flow events detected by conditional sampling applied to velocities in the log region may be related to the bursting process.
Document ID
19820048401
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Robinson, S. K.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 10, 2013
Publication Date
June 1, 1982
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
AIAA PAPER 82-0963
Meeting Information
Meeting: Joint Thermophysics, Fluids, Plasma and Heat Transfer Conference
Location: St. Louis, MO
Start Date: June 7, 1982
End Date: June 11, 1982
Sponsors: American Institute of Aeronautics and Astronautics and American Society of Mechanical Engineers
Accession Number
82A31936
Distribution Limits
Public
Copyright
Other

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