Effect of preferential concentration on the settling velocity of heavy particles in homogeneous isotropic turbulence
Effect of preferential concentration on the settling velocity of heavy particles in homogeneous isotropic turbulence
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DOI：
10.1017/s0022112002001593
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发表时间：
2002-10-10
影响因子：
3.7
通讯作者：
Lasheras, JC
中科院分区：
文献类型：
--
作者：
Aliseda, A;Cartellier, A;Lasheras, JC
对重颗粒在各向同性、均匀、衰减湍流中的行为进行了实验研究。研究发现，颗粒在静止流体中的沉降速度比在静止流体中大得多。结果表明，沉降速度的提高与颗粒负荷有关，颗粒负荷随颗粒体积分数的增加而增大。颗粒浓度场的时空分布表现出很大的不均匀性。当颗粒与底层湍流相互作用时，它们优先集中在流动的某些区域。发现这些颗粒团的特征尺寸与流动的粘性尺度有关。以局部颗粒浓度为条件的沉降速度测量表明，沉降速度与局部浓度呈单调递增关系(呈准线性关系)。提出了一个简单的现象学模型来解释这一行为。
The behaviour of heavy particles in isotropic, homogeneous, decaying turbulence has been experimentally studied. The settling velocity of the particles has been found to be much larger than in a quiescent fluid. It has been determined that the enhancement of the settling velocity depends on the particle loading, increasing as the volume fraction of particles in the flow increases. The spatial and temporal distribution of the particle concentration field is shown to exhibit large inhomogeneities. As the particles interact with the underlying turbulence they concentrate preferentially in certain regions of the flow. A characteristic dimension of these particle clusters is found to be related to the viscous scales of the flow. Measurements of the settling velocity conditioned on the local concentration of particles in the flow have shown that there is a monotonic increase in the settling velocity with the local concentration (the relation being quasi-linear). A simple phenomenological model is proposed to explain this behaviour.