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Attenuation of the wake of a sphere in an intense incident turbulence with large length scales

Amoura, Zouhir and Roig, Véronique and Risso, Frédéric and Billet, Anne-Marie Attenuation of the wake of a sphere in an intense incident turbulence with large length scales. (2010) Physics of Fluids, vol. 22 (n° 5). pp. 055105-055105. ISSN 1070-6631

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Official URL: http://dx.doi.org/10.1063/1.3425628

Abstract

We report an investigation of the wake of a sphere immersed in a uniform turbulent flow for sphere Reynolds numbers ranging from 100 to 1000. An original experimental setup has been designed to generate a uniform flow convecting an isotropic turbulence. At variance with previous works, the integral length scale of the turbulence is of the same order as the sphere diameter and the turbulence intensity is large. In consequence, the most intense turbulent eddies are capable of influencing the flow in the close vicinity of the sphere. Except in the attached region downstream of the sphere where the perturbation of the mean velocity is larger than the standard deviation of the incident turbulence, the flow is controlled by the incident turbulence. The distortion of the turbulence while the flow goes round the sphere leads to an increase in the longitudinal fluctuation and a decrease in the transversal one. The attenuation of the transversal fluctuations is still significant at 30 radii downstream of the sphere whereas the longitudinal fluctuations relax more rapidly toward the incident value. The more striking result however concerns the evolution of the mean velocity defect with the distance x from the sphere. It decays as x−2 and scales with the standard deviation of the incident turbulence instead of scaling with the mean incident velocity.

Item Type:Article
Additional Information:Thanks to American Institute of Physics . The definitive version is available at http://pof.aip.org/ The original PDF of the article can be found at : http://pof.aip.org/resource/1/phfle6/v22/i5/p055105_s1
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
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Deposited By:Audrey LEFEVRE

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