We investigate the dynamics of a dilute suspension of small, heavy particles superposed on a reservoir of still, pure fluid. The study is performed by means of numerical simulations of the Saffman model for a dilute particle suspension (Saffman, J. Fluid Mech., vol. 13, issue 1, 1962, pp. 120–128). In the presence of gravity forces, the interface between the two phases is unstable and evolves in a turbulent mixing layer which broadens in time. In the case of negligible particle inertia, the particle-laden phase behaves as a denser fluid, and the dynamics of the system recovers to that of the incompressible Rayleigh–Taylor set-up. Conversely, particles with large inertia affect the evolution of turbulent flow, delaying the development of turbulent mixing and breaking the up–down symmetry within the mixing layer. The inertial dynamics also leads to particle clustering, characterised by regions with higher particle density than the initial uniform density, and by the increase of the local Atwood number.

中文翻译：

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尘土飞扬的瑞利-泰勒湍流中的惯性效应

我们研究了叠加在静止纯流体储层上的小而重粒子的稀释悬浮液的动力学。该研究是通过对稀颗粒悬浮液的萨夫曼模型（萨夫曼，J.流体机械。, 卷。13，第 1 期，1962，第 120-128 页）。在存在重力的情况下，两相之间的界面是不稳定的，并演变成一个随时间变宽的湍流混合层。在粒子惯性可忽略不计的情况下，载有粒子的相表现为更稠密的流体，系统的动力学恢复到不可压缩的瑞利-泰勒设置的动力学。反之，惯性大的粒子会影响湍流的演化，延缓湍流混合的发展，破坏混合层内的上下对称性。惯性动力学也导致粒子聚集，其特征是粒子密度高于初始均匀密度的区域，以及局部阿特伍德数的增加。