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arXiv · 1312.6514

Active Microrheology of Driven Granular Particles

Ting Wang·Matthias Grob·Annette Zippelius·Matthias Sperl
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Abstract

When pulling a particle in a driven granular fluid with constant force $F_{ex}$, the probe particle approaches a steady-state average velocity $v$. This velocity and the corresponding friction coefficient of the probe $ζ=F_{ex}/v$ are obtained within a schematic model of mode-coupling theory and compared to results from event-driven simulations. For small and moderate drag forces, the model describes the simulation results successfully for both the linear as well as the nonlinear region: The linear response regime (constant friction) for small drag forces is followed by shear thinning (decreasing friction) for moderate forces. For large forces, the model demonstrates a subsequent increasing friction in qualitative agreement with the data. The square-root increase of the friction with force found in [Fiege et al., Granular Matter $\boldsymbol{14}$, 247 (2012)] is explained by a simple kinetic theory.

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Ting Wang, Matthias Grob, Annette Zippelius, Matthias Sperl. 2013-12-23. Active Microrheology of Driven Granular Particles. https://doi.org/10.1103/physreve.89.042209

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