Turbulence modulation by inertial-range-size, neutrally-buoyant particles is
investigated experimentally in a von K\'arm\'an flow. Increasing the particle
volume fraction $\Phi_\mathrm{v}$, maintaining constant impellers Reynolds
number attenuates the fluid turbulence. The inertial-range energy transfer rate
decreases as $\propto\Phi_\mathrm{v}^{2/3}$, suggesting that only particles
located on a surface affect the flow. Small-scale turbulent properties, such as
structure functions or acceleration distribution, are unchanged. Finally,
measurements hint at the existence of a transition between two different
regimes occurring when the average distance between large particles is of the
order of the thickness of their boundary layers.Comment: 7 pages, 4 figure

E. Bodenschatz

E.-W. Saw

Gatignol R.

J. Bec

M. Cisse

M. Gibert

English

arXiv

International audienceTurbulence modulation by inertial-range-size, neutrally-buoyant particles is investigated experimentally in a von Kármán flow. Increasing the particle volume fraction Φ v , maintaining constant impellers Reynolds number attenuates the fluid turbulence. The inertial-range energy transfer rate decreases as ∝ Φ 2/3 v , suggesting that only particles located on a surface affect the flow. Small-scale turbulent properties, such as structure functions or acceleration distribution, are unchanged. Finally , measurements hint at the existence of a transition between two different regimes occurring when the average distance between large particles is of the order of the thickness of their boundary layers. Introducing impurities in a developed turbulent flow has drastic effects on the mechanisms of energy transfer and dissipation. A minute amount of polymer additives causes for instance drag reduction. 1 In such visco-elastic fluids, the coupling between the local flow and the polymers stretching can be modeled in order to quantify the exchanges between kinetic and elastic energies and to interpret turbulent drag reduction as a suppression of large velocity gradients. 2 The mechanisms at play in turbulent suspensions of finite-size spherical particles are much more intricate and turbulence can either be enhanced or suppressed

Cisse, M

Saw, E.-W

Gibert, Mathieu

Bodenschatz, E

Bec, J

HAL Descartes

Turbulence attenuation by large neutrally buoyant particles

Turbulence modulation by inertial-range-size, neutrally buoyant particles is investigated experimentally in a von K?rm?n flow. Increasing the particle volume fraction �v, maintaining constant impellers Reynolds number attenuates the fluid turbulence. The inertial-range energy transfer rate decreases as ? �2/3 v , suggesting that only particles located on a surface affect the flow. Small-scale turbulent properties, such as structure functions or acceleration distribution, are unchanged. Finally, measurements hint at the existence of a transition between two different regimes occurring when the average distance between large particles is of the order of the thickness of their boundary layers

Cisse, M.

Saw, E.

Gibert, M.

Bodenschatz, E. 

Bec, J.

MPG.PuRe

HAL: Hyper Article en Ligne

Hal - Université Grenoble Alpes

Crossref

Physics of Fluids

Turbulence modulation by inertial-range-size, neutrally buoyant particles is investigated experimentally in a von Karman flow. Increasing the particle volume fraction Phi(v), maintaining constant impellers Reynolds number attenuates the fluid turbulence. The inertial-range energy transfer rate decreases as proportional to Phi(2/3)(v), suggesting that only particles located on a surface affect the flow. Small-scale turbulent properties, such as structure functions or acceleration distribution, are unchanged. Finally, measurements hint at the existence of a transition between two different regimes occurring when the average distance between large particles is of the order of the thickness of their boundary layers. (C) 2015 AIP Publishing LLC

Turbulence attenuation by large neutrally buoyant particles

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Hal - Université Grenoble Alpes

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