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arXiv 2401.16992physics.flu-dyn
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垂直壁面附近的气泡上升:路径与速度的实验表征

Bubble rising near a vertical wall: experimental characterization of paths and velocity

Cecilia Estepa-Cantero, Carlos Martínez-Bazán, Rocío Bolaños-Jiménez

AI总结:

本研究通过实验探究垂直壁面附近不同上升状态气泡的运动特性,分析三个控制参数的影响,发现壁面会引发气泡远离迁移、改变之字形运动平面,且壁面位置不同排斥效应强度有差异。

摘要:

本文通过实验研究了单个气泡在垂直固体壁面附近上升的运动轨迹。针对三种不同的气泡上升状态(即直线上升、平面之字形上升和螺旋上升),考察了不同的初始壁面-气泡间距。该问题由三个控制参数定义:伽利略数$Ga$、邦德数$Bo$,以及气泡质心与壁面的初始无量纲距离$L$。本文聚焦高邦德数情形,将$L$在1到4的范围内变化,并将结果与对应的无边界情形($L \rightarrow \ff$)进行对比。在所有情形下,气泡都会偏离预期的无边界轨迹,并且由于气泡与壁面之间的间隙中产生的超压,气泡在上升过程中会向远离壁面的方向迁移。初始壁面-气泡间距越小,这种排斥效应越明显。此外,在平面之字形上升状态下,当$L$足够小时,壁面会迫使气泡的之字形运动平面与壁面垂直。在速度或振荡幅度与频率方面,仅观测到轻微的壁面效应。壁面迁移效应在平面之字形情形中最为显著,在直线上升情形中影响较小。最后,本文还研究了壁面垂直位置的影响。当气泡释放时壁面不存在时,气泡表现出无边界情形下的预期行为,仅在到达壁面边缘前的瞬间才会发生迁移。总体而言,这种排斥效应比壁面初始存在的情形更为显著。

英文摘要:

The trajectories of a single bubble rising in the vicinity of a vertical solid wall are experimentally investigated. Distinct initial wall-bubble distances are considered for three different bubble rising regimes, i.e. rectilinear, planar zigzag, and spiral. The problem is defined by three control parameters, namely the Galilei number, $Ga$, the Bond number, $Bo$, and the initial dimensionless distance between the bubble centroid and the wall, $L$. We focus on high-Bond numbers, varying $L$ from 1 to 4, and compare the results with the corresponding unbounded case, $L \rightarrow \infty$. In all cases, the bubble deviates from the expected unbounded trajectory and migrates away from the wall as it rises due to the overpressure generated in the gap between the bubble and the wall. This repulsion is more evident as the initial wall-bubble distance decreases. Moreover, in the planar zigzagging regime, the wall is found to impose a preferential zigzagging plane perpendicular to it when $L$ is small enough. Only slight wall effects are observed in the velocity or the oscillation amplitude and frequency. The wall migration effect is more evident for the planar zigzagging case and less relevant for the rectilinear one. Finally, the influence of the vertical position of the wall is also investigated. When the wall is not present upon release, the bubbles have the expected behavior for the unbounded case and experience the migration only instants before reaching the wall edge. This repulsion is, in general, more substantial than in the initially-present-wall case.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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