Journal of Fluid Mechanics



Influence of wall suction on the organized motion in a turbulent boundary layer


R. A.  Antonia a1, L.  Fulachier a2, L. V.  Krishnamoorthy a2, T.  Benabid a2 and F.  Anselmet a2
a1 Department of Mechanical Engineering, University of Newcastle, NSW, 2308, Australia
a2 Institut de Mécanique Statistique de la Turbulence, Université d’ Aix-Marseille, 13003 Marseille, France

Article author query
antonia ra   [Google Scholar] 
fulachier l   [Google Scholar] 
krishnamoorthy lv   [Google Scholar] 
benabid t   [Google Scholar] 
anselmet f   [Google Scholar] 
 

Abstract

The effect of wall suction on the organized motion of a tubulent boundary layer is examined experimentally both in a wind tunnel and in a water tunnel. In the windtunnel boundary layer, which developed over a slighly heated surface, temperature fluctuations were simultaneously obtained at several points, aligned in either the x (streamwise) or y (normal to the wall) direction. The temperature traces reveal the existence of two spatially coherent events, characterized either by a sudden decrease (cooling) or by a sudden increase (heating) of temperature. Estimates are presented for the average convection velocity, and average frequency of these events. The average convection velocity of ‘coolings’ is about 15% larger than that of ‘heatings’, the velocity of both events exhibiting an important local maximum in the buffer region. Near the wall, the convection velocity of both events is increased slightly by suction while their average frequency is reduced by suction. Away from the wall, the average inclination of ‘coolings’ and ‘heatings’ is about 40° without suction; suction does not alter the inclination of ‘coolings’ but increases that of ‘heatings’ to about 50°. Visualizations in the water tunnel indicate that suction increases the stability and the longitudinal coherence of low-speed streaks. They also show that suction reduces the average frequency of dye ejections into the outer layer.

(Published Online April 21 2006)
(Received December 1 1986)
(Revised October 12 1987)



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