Granular flow around a cylindrical obstacle in an inclined chute
Granular flow around a cylindrical obstacle in an inclined chute
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DOI：
10.1063/5.0101694
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发表时间：
2022-09
影响因子：
4.6
通讯作者：
X. Cui;Matthew J. Harris;M. Howarth;Daisy Zealey;Reegan Brown;Jonny Shepherd
中科院分区：
文献类型：
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作者：
X. Cui;Matthew J. Harris;M. Howarth;Daisy Zealey;Reegan Brown;Jonny Shepherd
冲击波和颗粒真空是研究颗粒材料行为的重要现象，因为冲击波作用下颗粒材料的流动特性发生了巨大变化，颗粒真空边界处又没有颗粒。本文采用实验和数值模拟相结合的方法研究了倾斜溜槽中自由面颗粒流绕圆柱形障碍物的运动，分别采用离散元法和深度平均颗粒模型，从微观和宏观两个尺度上分析了颗粒流与障碍物的碰撞发展随时间的变化规律。使用高速摄像机的结果作为基准解决方案，冲击的解决方案之间的比较实验和仿真。DEM模拟显示其冲击形成更好的协议，因为它是能够捕捉固体，液体和气体的行为的冲击区，而深度平均模型提供了更接近和更简单的协议跨越冲击的跳跃解决方案。从实验和模拟结果表明，颗粒冲击波可以引起一个固-液-气的行为以下的流动周围的障碍物的传播，其中，在障碍物的前面，冲击区可以被视为一个固体政权的流动变得静止在颗粒流的主要过程。随着流动向下游传播，激波区显著扩展，并表现出强烈的液体和气体行为。另一个混合的液体和气体的颗粒流的行为也观察到以下的外观的颗粒真空，其中本地化的[公式：见正文]-流变学被证明是有效的，在解决真空边界的数值模拟。
Shock waves and granular vacua are important phenomena for studying the behavior of granular materials due to the dramatic change in flow properties across shock wave and the particle-free feature at the boundary of granular vacuum. In this paper, we use experiment and numerical simulation to study the granular free-surface flow past a cylindrical obstacle in an inclined chute, where the time-dependent development of the granular flow impacting the obstacle is analyzed at both microscopic and macroscopic scales using the discrete element method (DEM) and the depth-averaged granular model, respectively. Using high-speed camera results as a benchmark solution, the shock solutions are compared between experiment and simulation. The DEM simulation shows better agreement for its shock formation as it is capable of capturing solid, liquid, and gas behaviors for the shock region, while the depth-averaged model provides closer and simpler agreement for the jump solution across the shock. It is shown from the experiment and simulation that the granular shock wave can give rise to a solid–liquid–gas behavior following the propagation of the flow around the obstacle, where, at the front of the obstacle, the shock region can be regarded as a solid regime as the flow becomes stationary during the primary course of the granular flow. With the flow propagating to the downstream, the shock region extends significantly and exhibits strong liquid and gas behavior. Another mixed liquid and gas behavior of granular flow is also observed following the appearance of the granular vacuum, where a localized [Formula: see text]-rheology is shown to be effective in resolving the vacuum boundary in the numerical simulation.