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Particle capture by drops in turbulent flow
Physical Review Fluids ( IF 2.7 ) Pub Date : 2021-02-05 , DOI: 10.1103/physrevfluids.6.024303
Arash Hajisharifi , Cristian Marchioli , Alfredo Soldati

We examine the process of particle capture by large deformable drops in turbulent channel flow. We simulate the solid-liquid-liquid three-phase flow with an Eulerian-Lagrangian method based on direct numerical simulation of turbulence coupled with a phase-field model, to capture the interface dynamics, and Lagrangian tracking of small (sub-Kolmogorov) particles. Drops have the same density and viscosity of the carrier liquid, and neutrally buoyant, quasi-inertialess, solid particles are one-way coupled with the other phases. Our results show that particles are transported towards the interface by jetlike turbulent motions and, once close enough, are captured by interfacial forces in regions of positive surface velocity divergence. These regions appear to be well correlated with high-enstrophy flow topologies that contribute to enstrophy production via vortex compression or stretching. Examining the turbulent mechanisms that bring particles to the interface, we have been able to derive a simple transport model for particle capture. The model is based on a single turbulent transport equation in which the only parameter scales with the turbulent kinetic energy of the fluid measured in the vicinity of the drop interface, and its predictions of the overall capture efficiency agree remarkably well with numerical results.

中文翻译:

湍流中的液滴捕获颗粒

我们检查了湍流通道中大的可变形液滴捕获颗粒的过程。我们基于湍流的直接数值模拟和相场模型,基于欧拉-拉格朗日方法,通过固相-液-液三相流模拟,以捕获界面动力学,并对小(亚-科莫哥罗夫)小颗粒进行拉格朗日跟踪。液滴具有与载液相同的密度和粘度,并且中性浮力,准惯性固体颗粒与其他相单向耦合。我们的结果表明,颗粒通过射流状的湍流运动向界面传输,一旦足够接近,就会被界面力在正表面速度发散区域捕获。这些区域似乎与通过涡流压缩或拉伸有助于产生大涡流的高涡流形态密切相关。通过检查将粒子带到界面的湍流机制,我们已经能够得出用于粒子捕获的简单传输模型。该模型基于单个湍流输运方程,其中唯一的参数与在液滴界面附近测得的流体的湍动能成比例,并且其总体捕获效率的预测与数值结果非常吻合。
更新日期:2021-02-05
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