Numerical and Theoretical Modeling of Droplet Impact on Spherical Surfaces
Numerical and Theoretical Modeling of Droplet Impact on Spherical Surfaces
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DOI：
10.1063/5.0047024
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
Hussein N. Dalgamoni;Xin Yong
中科院分区：
文献类型：
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作者：
Hussein N. Dalgamoni;Xin Yong
液滴对固体表面的冲击是一种流体现象，广泛应用于增材制造、热管理和涂层，其中控制冲击动力学和持续时间的能力至关重要。虽然过去的研究已经建立了对平面基材影响的全面理解，但我们对弯曲固体表面的影响动力学的了解仍然有限。本文采用轴对称晶格玻尔兹曼方法（LBM）和理论分析相结合的方法，研究液滴撞击不同半径和表面润湿性的球形目标的物理特性。在我们以前的工作中发展的模型[H]。Dalgamoni和X. Yong，物理学家。对Rev. E 98, 13102(2018)]进行了扩展和修正，以模拟液滴变形轴对称假设成立的低韦伯数条件下液滴对弯曲基体的正常撞击。LBM模拟结果表明，液滴的表面几何形状和润湿性对液滴在撞击过程中的扩散和反冲有显著影响。参数研究揭示了五种影响结果，范围从完全沉积到完全反弹。建立了一个模拟预测相图，并与液滴与固体接触的总时间进行了关联。此外，建立了基于冲击过程能量收支的理论模型，独立预测目标半径和润湿性变化时的回弹阈值，与仿真结果吻合较好。这些发现为控制液滴流体动力学和撞击过程中接触时间的表面结构设计提供了基本的见解。
Droplet impact on solid surfaces is a fluid phenomenon widely involved in additive manufacturing, heat management, and coating, in which the ability to exert control over the impact dynamics and duration is critical. While past studies have established a comprehensive understanding of the impact on flat substrates, what we know about the impact dynamics on curved solid surfaces is still limited. This work aims to elucidate the physics of droplet impact on spherical targets with different radii and surface wettability using a combination of axisymmetric lattice Boltzmann method (LBM) and theoretical analysis. The model developed in our previous work [H. Dalgamoni and X. Yong, Phys. Rev. E 98, 13102 (2018)] was extended and modified for simulating the normal impact of droplet on curved substrates in the low Weber number regime, in which axisymmetric assumption of droplet deformation holds. The LBM simulations show that the surface geometry and wettability significantly affect the spreading and recoiling of droplet during impact. The parametric studies uncover five outcomes of impact, which range from complete deposition to total rebound. A simulation-predicted phase diagram was constructed and correlated with the total time that the droplet was in contact with the solid. In addition, a theoretical model based on energy budget during impact was developed to predict the rebound threshold when varying the target radius and wettability independently, which agrees well with simulation results. These findings provide fundamental insight into surface structure design for controlling droplet hydrodynamics and the contact time during impact.