Three-dimensional mesoscopic investigation of directional coalescence of two droplets impacting on a wall with wettability difference

IF 2.5 3区 工程技术 Q3 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS Computers & Fluids Pub Date : 2024-09-10 DOI:10.1016/j.compfluid.2024.106423
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Abstract

In this work, a three-dimensional (3D) nonorthogonal pseudopotential lattice Boltzmann method (LBM) was proposed to investigate the coalescence dynamics of two droplets impacting on a wall with wettability difference. The influences of the wettability difference, Weber number, offset distance on the low-wettability side on the coalescence dynamics and the contact-line evolution processes were systematically examined. Both symmetric and asymmetric distributions of the droplet-coalescence behaviors were considered. Our findings reveal that the wettability difference has a significant influence on the asymmetric-retracting and wetting-equilibrium stages, identifying three modes: pin-slip, slip and no-rebound, and slip and rebound. The rebound time is dominated by the high-wettability wall. At a larger Weber number, droplets exhibit a large retracting velocity, which results in increased pumping velocity and earlier rebound time. In addition, a dramatic retraction of the three-phase contact line (TPCL) on the low-wettability wall is observed, leading to the detachment of the liquid bridge from the low-wettability wall, and the formation of a cavity. With increasing offset distance on the low-wettability wall, three different evolution modes are found: coalescence-rebound, coalescence-separation, and non-coalescence. A power function relationship is reported between the Weber number We and the offset distance L* both on the high-wettability wall and low-wettability wall for three modes of coalescence behavior with WeL*α. The value of the exponent α ranges from 4.6 to 7.4. This study showcases the effectiveness of the 3D nonorthogonal pseudopotential LBM in predicting the complex interface phenomena and characteristics of the multiphase flow structures under investigation.

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对撞击到具有润湿性差异的壁上的两个液滴定向凝聚的三维介观研究
本研究提出了一种三维(3D)非正交伪势晶格玻尔兹曼方法(LBM)来研究两个液滴撞击具有润湿性差异的壁面时的凝聚动力学。系统研究了润湿性差异、韦伯数、低润湿性一侧的偏移距离对凝聚动力学和接触线演化过程的影响。研究同时考虑了液滴凝聚行为的对称分布和非对称分布。我们的研究结果表明,润湿性差异对非对称缩回和润湿平衡阶段有显著影响,并确定了三种模式:针滑、滑移和不回弹以及滑移和回弹。反弹时间由高润湿性壁面主导。韦伯数字越大,液滴的回缩速度越大,从而导致泵送速度增加和回弹时间提前。此外,还观察到低润湿壁上的三相接触线(TPCL)急剧收缩,导致液桥脱离低润湿壁,形成空腔。随着低润湿壁上偏移距离的增加,发现了三种不同的演化模式:凝聚-反弹、凝聚-分离和非凝聚。对于 We∼L*α 的三种凝聚行为模式,报告了高润湿壁和低润湿壁上韦伯数 We 与偏移距离 L* 之间的幂函数关系。指数 α 的取值范围为 4.6 至 7.4。本研究展示了三维非正交伪势 LBM 在预测所研究的多相流结构的复杂界面现象和特征方面的有效性。
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来源期刊
Computers & Fluids
Computers & Fluids 物理-计算机:跨学科应用
CiteScore
5.30
自引率
7.10%
发文量
242
审稿时长
10.8 months
期刊介绍: Computers & Fluids is multidisciplinary. The term ''fluid'' is interpreted in the broadest sense. Hydro- and aerodynamics, high-speed and physical gas dynamics, turbulence and flow stability, multiphase flow, rheology, tribology and fluid-structure interaction are all of interest, provided that computer technique plays a significant role in the associated studies or design methodology.
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