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Prevalence of the sling effect for enhancing collision rates in turbulent suspensions

Published online by Cambridge University Press:  23 May 2014

Michel Voßkuhle ,
Alain Pumir ,
Emmanuel Lévêque  and
Michael Wilkinson
Michel Voßkuhle
Affiliation:
Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS, Université de Lyon, 69007 Lyon, France
Alain Pumir*
Affiliation:
Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS, Université de Lyon, 69007 Lyon, France Max-Planck Institute for Dynamics and Self-Organisation, 37077 Göttingen, Germany
Emmanuel Lévêque
Affiliation:
Laboratoire de Mécanique des Fluides et d’Acoustique, Ecole Centrale de Lyon, CNRS, Université de Lyon, 69134 Ecully CEDEX, France
Michael Wilkinson
Affiliation:
Department of Mathematics and Statistics, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
*
†Email address for correspondence: alain.pumir@ens-lyon.fr
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Abstract

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Turbulence facilitates collisions between particles suspended in a turbulent flow. Two effects have been proposed that can enhance the collision rate at high turbulence intensities: ‘preferential concentration’ (a clustering phenomenon) and the ‘sling effect’ (arising from the formation of caustic folds in the phase space of the suspended particles). We have determined numerically the collision rate of small heavy particles as a function of their size and densities. The dependence on particle densities allows us to quantify the contribution of the sling effect to the collision rate. Our results demonstrate that the sling effect provides the dominant mechanism to the enhancement of the collision rate of particles, when inertia becomes significant.

JFM classification

Drops and Bubbles: Breakup/coalescence Drops and Bubbles: Drops and Bubbles Turbulent Flows: Turbulent Flows
Type
Papers
Information
Journal of Fluid Mechanics , Volume 749 , 25 June 2014 , pp. 841 - 852
Copyright
© 2014 Cambridge University Press 

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