Clustering dynamics of inertial particles in turbulent channel flow are studied via tessellation-based analysis of high-fidelity simulation data at with various values of mass loading () and the Stokes number (). We then characterise the solenoidal, rotational, and swirling motions of clusters by computing the probability density functions (PDFs) of the divergence, curl, and helicity of the particle velocity, as well as their dependence on wall-normal distance, using the methods of Oujia et al. (2020); Maurel–Oujia et al. (2023). Particle inertia gives heavier tails to the PDFs of divergence and curl, suggesting enhanced intermittency in the convergence/divergence of clusters, and in their rotational motions. The fluctuations of the divergence and curl are most intense in the buffer layer, due to the stronger fluctuations of fluid velocity there. Similarities are identified between the cluster dynamics in the logarithmic region and those in homogeneous isotropic turbulence, including the dependence of divergence, curl, and helicity on Stokes number. The effect of increasing mass loading on cluster dynamics is relatively small except in the viscous sublayer, where attenuation of clustering, rotation, and swirling motions are observed. The effect of increasing Stokes number on the viscous sublayer is different, resulting in more intense convergence/divergence and rotation of particle clusters, as the particles become more independent of the carrier fluid.

中文翻译：

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湍流通道流中惯性粒子的聚集、旋转和漩涡

通过对不同质量载荷 () 和斯托克斯数 () 值的高保真模拟数据进行基于曲面细分的分析，研究了湍流通道流中惯性粒子的聚类动力学。然后，我们通过计算粒子速度的散度、旋度和螺旋度的概率密度函数 (PDF) 以及它们对壁法向距离的依赖性，使用以下方法来表征簇的螺线管、旋转和漩涡运动：欧嘉等人。 （2020）；莫雷尔-欧嘉等人。 （2023）。粒子惯性使散度和旋度的 PDF 具有较重的尾部，表明簇的收敛/发散及其旋转运动的间歇性增强。由于缓冲层中流体速度的波动较强，散度和旋度的波动在缓冲层中最为强烈。对数区域中的团簇动力学与均匀各向同性湍流中的团簇动力学之间存在相似之处，包括散度、旋度和螺旋度对斯托克斯数的依赖性。除了在粘性次层中观察到团簇、旋转和漩涡运动的衰减之外，增加质量载荷对团簇动力学的影响相对较小。增加斯托克斯数对粘性子层的影响是不同的，随着颗粒变得更加独立于载液，导致颗粒簇的会聚/发散和旋转更加强烈。