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arXiv 2602.07348physics.flu-dyn
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速度、流体性质和液滴形状对合并与颈振荡的影响

Effect of velocity, fluid properties and drop shape on coalescence and neck oscillation

IITK(印度理工学院坎普尔分校)

Manas Ranjan Behera, Hiranya Deka, Kirti Chandra Sahu, Gautam Biswas

AI总结:

研究通过轴对称数值模拟探讨了液滴在深液池中的合并动力学,分析了速度、粘度和液滴形状对合并及颈振荡的影响,揭示了惯性、粘性和重力力在合并过程中的作用机制。

摘要:

我们通过轴对称数值模拟研究了液滴在深液池中的合并动力学。本研究旨在推广部分合并机制,阐明颈振荡的机理,并检验惯性、粘性和重力力(通过Weber、Ohnesorge和Bond数量化)在控制合并行为中的作用。构建了相图以基于这些无量纲参数区分部分和完全合并区域。分析高度与颈比显示,接触液体池时,主液滴形成向上的液柱,最终因向内方向的水平动量而破裂。此外,研究发现随着无量纲数增加,垂直坍缩率对合并过程结果的影响显著。值得注意的是,在探索的参数空间中,Rayleigh-Plateau不稳定性对部分合并的驱动作用不显著。我们识别了部分与完全合并之间的过渡区域,其特征是多个颈振荡延迟次级液滴的破裂。次级液滴的形成在纺锤形液滴中最为显著,随后是体积相当的球形和椭球形液滴。此外,我们观察到从伸长液柱形成多个液滴的倾向随着主液滴冲击速度的增加而减少。

英文摘要:

We perform axisymmetric numerical simulations to investigate the coalescence dynamics of a liquid drop in a deep liquid pool. This study aims to generalize the mechanisms of partial coalescence across a range of drop shapes, elucidate the underlying mechanism of neck oscillations, and examine the roles of inertial, viscous and gravitational forces, quantified by the Weber, Ohnesorge, and Bond numbers, in governing the coalescence behavior. A phase diagram is constructed to delineate the boundaries between partial and complete coalescence regimes based on these dimensionless parameters. Our analysis of the height-to-neck ratio shows that, upon contact with the pool, the primary drop forms an upward liquid column that ultimately pinches off due to inwardly directed horizontal momentum. Additionally, the study suggests that as the dimensionless numbers increase, the effect of the vertical collapse rate plays a significant role in the outcome of the coalescence process. Notably, the Rayleigh-Plateau instability is found to be insignificant in driving partial coalescence within the explored parameter space. We identified a transition regime between partial and complete coalescence, characterized by multiple neck oscillations that delay the pinch-off of secondary droplets. The formation of secondary droplets is most prominent for prolate drops, followed by spherical and oblate drops of comparable volume. Furthermore, we observe that the tendency to form multiple droplets from elongated liquid columns diminishes with an increase in the impact velocity of the primary drop.

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