Influence of Reynolds number and forcing type in a turbulent von Karman flow

Type Article
Date 2014-06
Language English
Author(s) Saint-Michel Brice1, Dubrulle B.1, Marie Louis2, Ravelet F.3, Daviaud F.1
Affiliation(s) 1 : CEA Saclay, CNRS URA 2464, DSM, Lab SPHYNX,Serv Phys Etat Condense, F-91191 Gif Sur Yvette, France.
2 : UMR 6523 CNRS IFREMER IRD UBO, Lab Phys Oceans, Brest, France.
3 : ENSAM ParisTech, CNRS EA92, Lab Dynfluid, F-75013 Paris, France.
Source New Journal Of Physics (1367-2630) (Iop Publishing Ltd), 2014-06 , Vol. 16 , N. 063037 , P. 1-27
DOI 10.1088/1367-2630/16/6/063037
WOS© Times Cited 2
Keyword(s) turbulence, instability, negative response, symmetry
Abstract We present a detailed study of a global bifurcation occuring in a turbulent von Karman swirling flow. In this system, the statistically steady states progressively display hysteretic behaviour when the Reynolds number is increased above the transition to turbulence. We examine in detail this hysteresis using asymmetric forcing conditions-rotating the impellers at different speeds. For very high Reynolds numbers, we study the sensitivity of the hysteresis cycle-using complementary particle image velocimetry and global mechanical measurements-to the forcing nature, imposing either the torque or the speed of the impellers. New mean states, displaying multiple quasi-steady states and negative differential responses, are experimentally observed in torque control. A simple analogy with electrical circuits is performed to understand the link between multi-stability and negative responses. The system is compared to other, similar 'bulk' systems, to understand some relevant ingredients of negative differential responses, and studied in the framework of thermodynamics of long-range interacting systems. The experimental results are eventually compared to the related problem of Rayleigh-Benard turbulence.
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