The role of collective effects on settling velocity enhancement for inertial particles in turbulence
The role of collective effects on settling velocity enhancement for inertial particles in turbulence
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DOI：
10.1017/jfm.2018.272
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发表时间：
2018-05
影响因子：
3.7
通讯作者：
P. Huck;C. Bateson;R. Volk;A. Cartellier;M. Bourgoin;A. Aliseda
中科院分区：
文献类型：
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作者：
P. Huck;C. Bateson;R. Volk;A. Cartellier;M. Bourgoin;A. Aliseda
通过实验研究了颗粒均匀各向同性湍流中的集体效应(如局部颗粒积累引起的颗粒-颗粒气动相互作用)对惯性颗粒(Stokes数：$0.3<；St<；0.6$)沉降速度的影响。颗粒垂直速度在局部浓度上的条件平均可分为三种沉降状态：低浓度区单颗粒-湍流相互作用的温和增强，中等浓度下团簇中的快速沉降速度增加，以及高浓度下的饱和沉降增强。与四向耦合有关的后一种效应与文献中的模拟定性一致，是一种新的实验观测结果。使用Vorono ai分析测量比背景体积分数大一个数量级的波动。根据经典的体积平均多相流方法建立了一个模型，以提供对三种沉淀区的解释和与测量结果一致的定量预测。
A particle-laden homogeneous isotropic turbulent flow is studied experimentally to understand the role of collective effects (e.g. particle–particle aerodynamic interactions caused by local particle accumulation) on the settling velocity of inertial particles (Stokes number: $0.3<St<0.6$ ). Conditional averaging of the particle vertical velocity on the local concentration identifies three settling regimes: modest enhancement by single particle–turbulence interactions in low concentration regions, rapid settling velocity increases in clusters at intermediate concentrations and saturation of the settling enhancement at large concentrations. The latter effect, associated with four-way coupling, displays qualitative agreement with simulations in the literature and is a new experimental observation. Fluctuations up to an order of magnitude larger than the background volume fraction are measured using Voronoï analysis. A model is developed following a classic volume-averaged multiphase flow methodology to provide an interpretation of the three settling regimes and quantitative predictions consistent with the measurements.