Bocquet L, Losert W, Schalk D, Lubensky T C, Gollub J P
Laboratoire de Physique de l'ENS de Lyon, UMR CNRS 5672, 46 Allée d'Italie, 69364 Lyon Cedex, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Jan;65(1 Pt 1):011307. doi: 10.1103/PhysRevE.65.011307. Epub 2001 Dec 21.
We analyze the main features of granular shear flow through experimental measurements in a Couette geometry and a comparison to a locally Newtonian, continuum model of granular flow. The model is based on earlier hydrodynamic models, adjusted to take into account the experimentally observed coupling between fluctuations in particle motion and mean-flow properties. Experimentally, the local velocity fluctuations are found to decrease more slowly with distance from the shear surface than the velocity. This can be explained by an effective viscosity that diverges more rapidly as the random-close-packing density is approached than is predicted by Enskog theory for dense hard-sphere systems. Experiment and theory are in good agreement, especially for the following key features of granular flow: The flow is confined to a small shear band, fluctuations decay approximately exponentially away from the sheared wall, and the shear stress is approximately independent of the shear velocity. The functional forms of the velocity and fluctuation profiles predicted by the model agree with the experimental results.
我们通过在库埃特几何结构中的实验测量，分析颗粒剪切流的主要特征，并将其与颗粒流的局部牛顿连续介质模型进行比较。该模型基于早期的流体动力学模型，并进行了调整，以考虑到实验观察到的颗粒运动波动与平均流特性之间的耦合。在实验中，发现局部速度波动随离剪切表面距离的减小比速度更慢。这可以用一种有效粘度来解释，当接近随机密堆积密度时，该有效粘度的发散速度比稠密硬球系统的恩斯科格理论预测的更快。实验与理论吻合良好，特别是对于颗粒流的以下关键特征：流动局限于一个小的剪切带，波动从剪切壁向外近似指数衰减，并且剪切应力近似与剪切速度无关。模型预测的速度和波动剖面的函数形式与实验结果一致。
