Benjamin Levich Institute, City College of New York, New York, New York 10031, USA.
Phys Rev Lett. 2013 Nov 22;111(21):218301. doi: 10.1103/PhysRevLett.111.218301. Epub 2013 Nov 18.
Discontinuous shear thickening (DST) observed in many dense athermal suspensions has proven difficult to understand and to reproduce by numerical simulation. By introducing a numerical scheme including both relevant hydrodynamic interactions and granularlike contacts, we show that contact friction is essential for having DST. Above a critical volume fraction, we observe the existence of two states: a low viscosity, contactless (hence, frictionless) state, and a high viscosity frictional shear jammed state. These two states are separated by a critical shear stress, associated with a critical shear rate where DST occurs. The shear jammed state is reminiscent of the jamming phase of granular matter. Continuous shear thickening is seen as a lower volume fraction vestige of the jamming transition.
在许多密集的无热悬浮液中观察到的不连续剪切增稠（DST），通过数值模拟很难理解和再现。通过引入一种包括相关流体动力学相互作用和颗粒状接触的数值方案，我们表明接触摩擦对于 DST 是必不可少的。在超过一个临界体积分数后，我们观察到存在两种状态：低粘度、无接触（因此无摩擦）状态和高粘度摩擦剪切堵塞状态。这两种状态由一个临界剪切应力隔开，该剪切应力与 DST 发生的临界剪切速率有关。剪切堵塞状态类似于颗粒物质的堵塞相。连续剪切增稠被视为堵塞转变的低体积分数遗迹。
