Fluctuations and diffusion in sheared athermal suspensions of deformable particles

¹ Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum Universitätsstraße 150, 44780 Bochum, Germany
² Max-Planck-Institut für Intelligente Systeme - Heisenbergstraße 3, 70569 Stuttgart, Germany
³ Institut für Theoretische Physik IV, Universität Stuttgart - Pfaffenwaldring 57, 70569 Stuttgart, Germany
⁴ School of Engineering, The University of Edinburgh - Edinburgh EH9 3JL, UK
⁵ Max-Planck Institut für Eisenforschung - Max-Planck Straße 1, 40237 Düsseldorf, Germany

^(a) gross@is.mpg.de (corresponding author)

Received: 26 August 2014
Accepted: 5 December 2014

Abstract

We analyze fluctuations of particle displacements and stresses in a sheared athermal suspension of elastic capsules (red blood cells). Upon variation of the volume fraction from the dilute up to the highly concentrated regime, our numerical simulations reveal different characteristic power-law regimes of the fluctuation variances and relaxation times. In the jammed phase and at high shear rates, anomalous scaling exponents are found that deviate from pure dimensional predictions. The observed behavior is rationalized via kinetic arguments and a dissipation balance model that takes into account the local fluid flows between the particles. Our findings support the view that the rheology of dense suspensions is essentially governed by the non-affine displacements.