The transport of liquid and of small rigid spherical particles in a high-Prandtl-number ($\text{Pr}=68$) thermocapillary liquid bridge under zero gravity is studied by highly resolved numerical simulations when the flow arises as an azimuthally traveling hydrothermal wave with azimuthal wave number one. The Langrangian transport of fluid elements reveals the coexistence of regular and chaotic streamlines in the frame of reference rotating with the wave. The structure of the KAM (Kolmogorov-Arnold-Moser) tori is unraveled for several Reynolds numbers for which the flow is periodic in time and space. Based on the streamline topology the segregation of small rigid spherical particles of a dilute suspension into particle accumulation structures (PASs) is studied, based on the steric finite-particle-size effect when the particles moves close to the free surface. It is shown that the intricate KAM structures have their counterparts in a multitude of different attractors for the particle motion. Examples of PASs are provided, and their dependence on particle size, particle-to-fluid density ratio, and Reynolds number are discussed. A large parametric study reveals the most probable combinations of particle size and density ratio which lead to particle clustering.

中文翻译：

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高普朗特数液桥中的有限尺寸相干粒子结构

液体和小刚性球形颗粒以高普朗特数的传输（$\text{压力}=68$) 零重力下的热毛细管液桥是通过高分辨率数值模拟研究的，当流动以方位角波数为 1 的方位角行进热液波出现时。流体元素的朗格朗日传输揭示了在随波旋转的参考系中规则和混沌流线的共存。KAM (Kolmogorov-Arnold-Moser) tori 的结构被解开为几个雷诺数，其中流动在时间和空间上是周期性的。基于流线拓扑，研究了稀悬浮液的刚性小球形颗粒分离成颗粒堆积结构 (PAS)，基于颗粒靠近自由表面移动时的空间有限颗粒尺寸效应。结果表明，复杂的 KAM 结构在许多不同的粒子运动吸引子中都有对应的结构。提供了 PAS 的示例，并讨论了它们对粒度、颗粒与流体密度比和雷诺数的依赖关系。一项大型参数研究揭示了最可能导致颗粒聚集的颗粒尺寸和密度比的组合。