ON THE PROBLEM OF USING PARTICLE IMAGE VELOCIMETRY FOR MEASUREMENTS IN HIGH-VELOCITY THIN SHEAR LAYERS

Experimental data on linear instability of the laminar separating flow and mean velocity characteristics of the turbulent boundary layer are reported. The results are obtained through wind-tunnel testing of Particle Image Velocimetry (PIV) performed at DLR, Goettingen. Details of the method, as applied to the above problems of fluid mechanics, are considered. The present findings seem helpful during experimental work on subsonic near-wall layers, when focusing on their instantaneous and time-mean velocity characteristics.

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Downstream particle image velocimetry measurements of a circular cylinder—plate junction

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/09544062jmes1446 ◽

2009 ◽

Vol 223 (8) ◽

pp. 1837-1849 ◽

Cited By ~ 2

Author(s):

N A Ozturk ◽

A Akcayoglu ◽

B Sahin

Keyword(s):

Particle Image Velocimetry ◽

Circular Cylinder ◽

Particle Image ◽

Flow Characteristics ◽

Horseshoe Vortex ◽

Shear Layers ◽

Wake Flow ◽

Piv Technique ◽

Image Velocimetry ◽

Series Of Experiments

In the present investigation, special attention was given to the flow characteristics downstream of a circular cylinder mounted on a flat surface for Reynolds numbers of 4000 and 7000. A series of experiments were performed in successive end-view planes with the range of 0≤ XL/ d≤5 using the particle image velocimetry (PIV) technique in order to demonstrate characteristics of wake flow structure and interactions between the shear layers caused by shedding vortices and tails of the horseshoe vortex system emanating from the upstream base of the cylinder. The development and growth of primary vortices in the end-view planes caused by the interactions of core flow and wake flow regions along the inner face of the shedding shear layers were examined quantitatively. Finally, it was concluded that the PIV technique was also capable of providing accurate velocity readings in the end-view planes of the wake flow regions.

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Some characteristics of thin shear layers in homogeneous turbulent flow

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2010.0297 ◽

2011 ◽

Vol 369 (1937) ◽

pp. 709-722 ◽

Cited By ~ 10

Author(s):

N. A. Worth ◽

T. B. Nickels

Keyword(s):

Particle Image Velocimetry ◽

Turbulent Flow ◽

Particle Image ◽

Isotropic Turbulence ◽

Shear Layers ◽

Tomographic Particle Image Velocimetry ◽

Homogeneous Isotropic Turbulence ◽

Image Velocimetry ◽

Large Velocity ◽

Made In

Tomographic particle image velocimetry measurements of homogeneous isotropic turbulence that have been made in a large mixing tank facility at Cambridge are analysed in order to characterize thin highly sheared regions that have been observed. The results indicate that such regions coincide with regions of high enstrophy, dissipation and stretching. Large velocity jumps are observed across the width of these regions. The thickness of the shear layers seems to scale with the Taylor microscale, as has been suggested previously. The results discussed here concentrate on examining individual realizations rather than statistics of these regions.

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