颗粒瑞利-泰勒不稳定性：实验与模拟
Granular Rayleigh-Taylor Instability: Experiments and Simulations
摘要：
对重力驱动的颗粒不稳定性进行了实验和数值研究。当颗粒落入封闭的Hele-Shaw单元中时，不稳定性出现，在封闭的Hele-Shaw单元中，一层致密的颗粒材料位于一层空气上方。最初由颗粒限定的平坦前部随后发展成由上升的气泡分开的下降的颗粒指状物的图案。从一开始就观察到的手指合并过程中的一个短暂的粗化的前面。粗化之后通过从上升气泡的中心生长的新指状物而稳定。通过傅立叶分析和实验和计算之间的定量协议的结构进行了量化。分析还揭示了在空间尺度整体变化的情况下，流场结构的尺度不变性。
英文摘要：
A granular instability driven by gravity is studied experimentally and numerically. The instability arises as grains fall in a closed Hele-Shaw cell where a layer of dense granular material is positioned above a layer of air. The initially flat front defined by the grains subsequently develops into a pattern of falling granular fingers separated by rising bubbles of air. A transient coarsening of the front is observed right from the start by a finger merging process. The coarsening is later stabilized by new fingers growing from the center of the rising bubbles. The structures are quantified by means of Fourier analysis and quantitative agreement between experiment and computation is shown. This analysis also reveals scale invariance of the flow structures under overall change of spatial scale.
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