Two spheres sedimentation dynamics in a viscous liquid column
Two spheres sedimentation dynamics in a viscous liquid column
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DOI：
10.1016/j.compfluid.2015.10.003
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发表时间：
2015-12
影响因子：
2.8
通讯作者：
S. M. Dash;T. Lee
中科院分区：
文献类型：
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作者：
S. M. Dash;T. Lee
在本文中，三维数值模拟和有限的实验研究结果的两个内联球在牛顿流体中的沉降在雷诺数（Re）为10至60的范围内。该研究的动机是[Fortes（1987）] [1]的实验，该实验表明两个沉降球独特地经历非线性尾流相互作用，该非线性尾流相互作用在领先球的低压尾流中捕获尾随球并加速其运动以形成一对接吻球，随后在以相同速度行进之前翻滚并分裂。本研究的目的是解决一些悬而未决的问题，表面压力分布，流体动力和诱导转向力偶作用在球的过程中的Drafting-Kissing-Tumbling（以下简称为DKT）。实验是在一个含有甘油-水的混合物的一个预定的粘度的垂直槽中进行的，并进行了数值研究，使用耦合浸没边界格子玻尔兹曼计划。除了DKT过程中的涡量场和压力分布，我们的数值结果表明，翻滚机制的影响，转动对，这与排斥流体动力学力一起起源垂直和横向迁移的领域，直到他们获得一个稳定的状态对齐。转动力偶的方向决定了球体是否会反转或反转翻滚机制。我们的研究结果进一步表明，归一化的轨迹，沉降速度和水动力系数的沉降球是独立的Re，至少在这里考虑的值的范围内。
In this paper, results of three-dimensional numerical simulation and limited experimental study are presented on the sedimentation of two inline spheres in a Newtonian fluid at a Reynolds number (Re) range of 10 to 60. The study is motivated by the experiment of [Fortes (1987)] [1], which shows that two settling spheres uniquely experience a non-linear wake interaction that captures the trailing sphere in the low pressure wake of the leading one and accelerates its motion to form a pair of kissing spheres, follows by tumbling and splitting apart before traveling with the same velocity. The present study aims to address some unanswered questions regarding surface pressure distributions, hydrodynamic forces and induced turning couples acting on the spheres during the process of Drafting-Kissing-Tumbling (henceforth refer to as DKT). The experiments were conducted in a vertical tank containing glycerine-water mixture of a predetermined viscosity, and the numerical study was performed using a coupled immersed boundary-lattice Boltzmann scheme. In addition to the vorticity field and pressure distributions during DKT, our numerical results indicate that the tumbling mechanism is influenced by the turning couple, which together with repulsive hydrodynamic forces originates vertical and lateral migrations of the spheres until they acquire a steady state alignment. The sense of the turning couple dictates whether the spheres would exhibitnormalorinversetumbling mechanism. Our results further show that normalised trajectories, settling velocities and hydrodynamics force coefficients of sedimenting spheres are independent of Re, at least for the range of values considered here.