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Simultaneous flow visualization and Reynolds-stress measurement in a turbulent boundary layer

Published online by Cambridge University Press:  21 April 2006

A. M. Talmon
Affiliation:
Delft University of Technology, Laboratory for Aerodynamics and Hydrodynamics, Delft, The Netherlands
J. M. G. Kunen
Affiliation:
Delft University of Technology, Laboratory for Aerodynamics and Hydrodynamics, Delft, The Netherlands
G. Ooms
Affiliation:
Delft University of Technology, Laboratory for Aerodynamics and Hydrodynamics, Delft, The Netherlands

Abstract

Flow visualization and Reynolds-stress measurement were combined in an investigation of a turbulent boundary layer in a water channel. Hydrogen bubbles were used to visualize the flow; a laser-Doppler anemometer capable of measuring two velocity components was applied to measure the instantaneous value of the Reynolds stress. Owing to the three-dimensional, time-dependent character of the flow it was rather difficult to identify flow structures from measured velocity signals, especially at larger distances from the wall. Despite this difficulty a method based on the instantaneous value of the Reynolds stress could be developed for detecting bursts in the wall region of the boundary layer. By this method the three-dimensional, time-dependent character of the flow is taken into account by attributing to the same burst ejections occurring successively with very short time intervals. This identification procedure is based on a comparison on a one-to-one basis between visualized flow structures and measured values of the Reynolds stress. The detected bursts were found to make a considerable contribution to the momentum transport in the boundary layer.

Type
Research Article
Copyright
© 1986 Cambridge University Press

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