Numerical study of hydrophobic micron particle's impaction on liquid surface
Numerical study of hydrophobic micron particle's impaction on liquid surface
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疏水微米颗粒撞击液体表面的数值研究
DOI：
10.1063/1.4991915
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发表时间：
2017-07-01
影响因子：
4.6
通讯作者：
Yao, Qiang
中科院分区：
文献类型：
--
作者：
Ji, Bingqiang;Song, Qiang;Yao, Qiang
本文建立了一种模拟微米级颗粒与液体表面碰撞的方法，研究了浸没和振荡两种碰撞方式下的碰撞过程。发现浸没过程经历了三个阶段，每个阶段的颗粒速度和气液界面变化具有不同的特征。淹没模式前期和后期的主导力分别为水动力和表面张力，其累积功的量级相同。损失的颗粒动能转化为界面的表面能、内能和流体的动能。振荡的主要部分是第一周期，其下沉过程的特征与淹没相似。在回复阶段，颗粒上升速度先增大后减小，空腔收缩，直至气液界面消失。回复阶段的前期和后期的主导力分别是表面张力和水动力。由于在回复阶段的早期时间的大的接触角滞后，表面张力对颗粒的正累积功相当有限。后期流体动力作用在颗粒上的负积功使颗粒动能迅速下降，导致颗粒浮在气液界面上。研究结果有助于了解微米颗粒碰撞的机理和发展附着效率的预测方法。出版社：AIP Publishing
In this study, a simulation method is established for the impaction of micron particles on liquid surfaces, by which the processes of two impaction modes (submergence and oscillation) are studied. The submergence is found to go through three stages, each of which shows different characteristics of particle velocity and gas-liquid interface variance. The dominant forces of the early and late times of the submergence mode are hydrodynamic force and surface tension, respectively, the accumulated work of which is in the same order. The lost particle kinetic energy is converted to the surface energy of the interfaces, the internal energy and the kinetic energy of fluids. The primary part of the oscillation is the first cycle, and the characteristics of its sinking process are similar to that of the submergence. In the reverting stage, the particle rising velocity increases first and then decreases, and the cavity retracts until the gas-liquid interface flattens. The dominant forces of the early and late times of the reverting stage are surface tension and hydrodynamic force, respectively. The positive accumulated work of surface tension on the particle is considerably limited due to the large contact angle hysteresis at the early times of the reverting stage. The negative accumulated work of the hydrodynamic force on the particle at the late times causes a fast decrease in particle kinetic energy, which leads to particle floating on the gas-liquid interface. The results are helpful in understanding the mechanism of micron particle impaction and developing the prediction method of attachment efficiency. Published by AIP Publishing.