Effect of Gravity on Particle Clustering and Collisions in Decaying Turbulence
Effect of Gravity on Particle Clustering and Collisions in Decaying Turbulence
复制标题
重力对衰变湍流中粒子聚集和碰撞的影响
DOI：
10.1007/s10494-023-00402-9
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Nair V
中科院分区：
文献类型：
--
作者：
Nair V
利用径向分布函数(RDF)研究了均匀各向同性湍流衰减过程中沉积颗粒的优先浓度。直接数值模拟了半径为10-55μm的非沉淀物和沉淀物的多分散性分布。我们看到了RDF在衰减湍流中的幂定律行为，以及Chun等人推导出的幂定律关系。(J Fluid Mech 536：219-251,2005)对于非沉降性颗粒的RDF也适用于沉降性颗粒。给出了沉降颗粒的幂定律系数的经验公式，这些系数是斯托克斯数和泰勒雷诺数的函数。对非沉积碰撞核和沉积碰撞核的湍流运动碰撞核的深入分析证实，重力增强了不等尺寸颗粒的碰撞核，而减小了相同尺寸颗粒的碰撞核。建立了单分散和双分散RDF的模型，并与现有的碰撞颗粒条件径向相对速度模型相结合，预测了非沉积颗粒和沉积颗粒的运动碰撞核。本文还探讨了湍流对碰撞核的影响，并观察到与引力碰撞核相比，碰撞核的倍数增加了三倍。
The preferential concentration of sedimenting particles in decaying homogeneous isotropic turbulence is investigated using radial distribution functions (RDF). Direct numerical simulations of polydisperse distributions of non-sedimenting and sedimenting particles of radii 10–55 μm are performed. We see a power law behaviour for the RDF in decaying turbulence and the power-law relation derived by Chun et al. (J Fluid Mech 536:219–251, 2005) for the RDF of non-sedimenting particles holds for sedimenting particles as well. Empirical formulas are generated for the power-law coefficients which are shown to be functions of the Stokes number and the Taylor Reynolds number for sedimenting particles. An in-depth analysis of the turbulent kinematic collision kernel for both non-sedimenting and sedimenting collision kernels confirms that gravity enhances the collision kernel for unequal sized particles and decreases for same-sized particles. Models are created for both monodisperse and bidisperse RDFs which are combined with existing models for the conditional radial relative velocities of colliding particles to predict kinematic collision kernels for both non-sedimenting and sedimenting particles. The effect on the collision kernel due to turbulence is also explored and enhancement of factors of up to three is observed with respect to the gravitational collision kernel.
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