Physique et Mécanique des Milieux Hétérogènes, UMR 7636 ESPCI-CNRS, Université Paris-Diderot, Université P.M. Curie, 10 rue Vauquelin, 75005 Paris, France.
Phys Rev Lett. 2012 Sep 14;109(11):118305. doi: 10.1103/PhysRevLett.109.118305.
Non-Brownian suspensions present a transition from Newtonian behavior in the zero-shear limit to a shear thickening behavior at a large shear rate, none of which is clearly understood so far. Here, we carry out numerical simulations of such an athermal dense suspension under shear, at an imposed confining pressure. This setup is conceptually identical to recent experiments of Boyer, Guazzelli, and Pouliquen [Phys. Rev. Lett. 107, 188301 (2011)]. Varying the interstitial fluid viscosities, we recover the Newtonian and Bagnoldian regimes and show that they correspond to a dissipation dominated by viscous and contact forces, respectively. We show that the two rheological regimes can be unified as a function of a single dimensionless number, by adding the contributions to the dissipation at a given volume fraction.
无布朗运动悬浮液在零剪切极限下表现出牛顿行为，而在大剪切速率下表现出剪切增稠行为，目前这些行为都没有得到清晰的理解。在这里，我们在施加的围压下对这种无热密悬浮液进行了剪切下的数值模拟。这种设置在概念上与 Boyer、Guazzelli 和 Pouliquen 的最近实验相同[Phys. Rev. Lett. 107, 188301 (2011)]。通过改变中间流体的粘度，我们恢复了牛顿和 Bagnold 区，并表明它们分别对应于由粘性和接触力主导的耗散。我们表明，通过在给定的体积分数下添加耗散的贡献，可以将这两个流变区统一为一个单一的无量纲数的函数。
