Particle accumulation structures in noncylindrical liquid bridges under microgravity conditions
Particle accumulation structures in noncylindrical liquid bridges under microgravity conditions
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DOI：
10.1103/physrevfluids.5.084304
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发表时间：
2020-08-14
影响因子：
2.7
通讯作者：
Lappa, Marcello
中科院分区：
文献类型：
--
作者：
Capobianchi, Paolo;Lappa, Marcello
对考虑微重力条件下高普朗特数液体的非圆柱形液体桥中粒子积累结构（PAS）的产生进行了数值研究。模拟是在有限体积（欧拉）方法的框架下进行的，使用拉格朗日单向耦合方案跟踪非等密度粒子。首先，将马兰戈尼流不稳定性阈值确定为长径比和支撑盘间液体体积的函数，然后，研究超临界条件下PAS的形成。整体的方法是特别设想，以提供有关这些结构的形态演变的细节，因为主要控制参数是变化的。出于这个原因，引入了一套专门的概念和定义（如PAS的线性扩展，其内核半径，以及“花瓣”或“叶片”的面积），以允许对一系列纯几何效果进行精确量化。虽然分析被故意限制在说明宏观模式行为及其与总体因素的关系，但提出了一个模型来解释细长（凹）lb在粒子斯托克斯数的扩展值范围内支持PAS形成的能力增加。该模型仍然主要依赖于几何参数，即自由表面曲率、流体流线拓扑和粒子质量效应之间的三元关系。
The emergence of particle accumulation structures (PAS) in noncylindrical liquid bridges (LBs) is studied numerically for a high Prandtl number liquid considering microgravity conditions. Simulations are conducted in the framework of a finite-volume (Eulerian) approach with nonisodense particles tracked using a Lagrangian, one-way coupling scheme. First, the threshold of the Marangoni-flow instability is determined as a function of the aspect ratio and the volume of liquid held between the supporting disks, thereafter, PAS formation is investigated for supercritical conditions. The overall approach is specifically conceived to provide details about the morphological evolution of these structures as the main control parameters are varied. For this reason a set of dedicated notions and definitions (such as the linear extension of the PAS, its inner core radius, and the area of the "petals" or "blades") are introduced to allow a precise quantification of a series of purely geometrical effects. Though the analysis is deliberately limited to illustrating the macroscopic patterning behavior and its relationship with the overarching factors, a model is proposed to interpret the increased ability of slender (concave) LBs to support the formation of PAS over extended ranges of values of the particle Stokes number. This model yet relies on essentially geometrical arguments, that is, the triadic relationship among the curvature of the free surface, the topology of fluid streamlines, and particle mass effects.