Physique et Mécanique des Milieux Hétérogènes, UMR 7636 ESPCI -CNRS, Univ. Paris-Diderot, 10 rue Vauquelin, 75005, Paris.
Phys Rev Lett. 2012 Sep 7;109(10):105901. doi: 10.1103/PhysRevLett.109.105901. Epub 2012 Sep 6.
The dynamical mechanisms controlling the rheology of dense suspensions close to jamming are investigated numerically, using simplified models for the relevant dissipative forces. We show that the velocity fluctuations control the dissipation rate and therefore the effective viscosity of the suspension. These fluctuations are similar in quasi-static simulations and for finite strain rate calculations with various damping schemes. We conclude that the statistical properties of grain trajectories-in particular the critical exponent of velocity fluctuations with respect to volume fraction φ-only weakly depend on the dissipation mechanism. Rather they are determined by steric effects, which are the main driving forces in the quasistatic simulations. The critical exponent of the suspension viscosity with respect to φ can then be deduced, and is consistent with experimental data.
本文通过数值模拟，利用简化模型研究了接近堵塞的密集悬浮液流变学的动力学机制。我们表明，速度波动控制着悬浮液的耗散率和有效粘度。这些波动在准静态模拟和不同阻尼方案的有限应变率计算中是相似的。我们得出结论，颗粒轨迹的统计特性——特别是速度波动相对于体积分数φ的临界指数——仅与耗散机制弱相关。相反，它们由空间效应决定，空间效应是准静态模拟中的主要驱动力。悬浮液粘度相对于φ的临界指数可以推断出来，并且与实验数据一致。
