Richards J A, Royer J R, Liebchen B, Guy B M, Poon W C K
SUPA, School of Physics and Astronomy, The University of Edinburgh, King's Buildings, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom.
Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany.
Phys Rev Lett. 2019 Jul 19;123(3):038004. doi: 10.1103/PhysRevLett.123.038004.
Competing timescales generate novelty. Here, we show that a coupling between the timescales imposed by instrument inertia and the formation of interparticle frictional contacts in shear-thickening suspensions leads to highly asymmetric shear-rate oscillations. Experiments tuning the presence of oscillations by varying the two timescales support our model. The observed oscillations give access to a shear-jamming portion of the flow curve that is forbidden in conventional rheometry. Moreover, the oscillation frequency allows us to quantify an intrinsic relaxation time for particle contacts. The coupling of fast contact network dynamics to a slower system variable should be generic to many other areas of dense suspension flow, with instrument inertia providing a paradigmatic example.
相互竞争的时间尺度产生了新奇现象。在此，我们表明，仪器惯性所施加的时间尺度与剪切增稠悬浮液中颗粒间摩擦接触的形成之间的耦合会导致高度不对称的剪切速率振荡。通过改变这两个时间尺度来调节振荡存在情况的实验支持了我们的模型。观察到的振荡使我们能够进入传统流变学中被禁止的流动曲线的剪切堵塞部分。此外，振荡频率使我们能够量化颗粒接触的固有弛豫时间。快速接触网络动力学与较慢系统变量的耦合在许多其他密集悬浮液流动领域中应该是普遍存在的，仪器惯性就是一个典型例子。
