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Bubble Drag in Electrolytically Generated Microbubble Swarms with Bubble-Vortex Interactions
International Journal of Multiphase Flow ( IF 3.6 ) Pub Date : 2021-03-01 , DOI: 10.1016/j.ijmultiphaseflow.2020.103541
Yasunori Watanabe , Haruhi Oyaizu , Hisashi Satoh , Yasuo Niida

Abstract Air bubbles entrained in ocean breaking waves play various roles in air–sea gas transfer, wave energy dissipation, and surface layer mixing. While sub-mm bubbles dominate the distribution of sizes observed in bubble plumes created by breaking waves, the dynamics of such microbubbles in a swarm are poorly understood, and most previous experimental and computational studies have focused on the behavior of homogeneous swarms of larger mm-scale bubbles for industrial applications. Here, we propose novel probabilistic empirical models of rise velocity and bubble drag for a microbubble swarm incorporating bubble–vortex interactions. These are based on image measurements of the motion of electrolytically generated microbubbles. We found that convective interactions between bubbles and vortex-induced flows, that is, Rayleigh–Taylor instability caused by density difference near the electrodes, induce counter-rotating vortices that accelerate bubbles and align them along paths in the flow induced between them, resulting in an increase in rise velocity and its variance in the statistical equilibrium state. We describe the statistical features of bubble rise in such swarms in our proposed empirical model and deduce its optimal parameters. We anticipate our findings being a starting point for understanding behaviors of oceanic bubbles possessing an analogous size distribution to the present electrolytically generated microbubbles.

中文翻译:

具有气泡-涡流相互作用的电解产生的微气泡群中的气泡阻力

摘要 海浪中夹带的气泡在海气传递、波浪能耗散和表层混合中发挥着多种作用。虽然亚毫米气泡在由破碎波产生的气泡羽流中观察到的尺寸分布占主导地位,但人们对群体中此类微气泡的动力学知之甚少,而且大多数先前的实验和计算研究都集中在较大毫米的同质群体的行为上。工业应用的规模气泡。在这里,我们为包含气泡 - 涡流相互作用的微气泡群提出了上升速度和气泡阻力的新概率经验模型。这些是基于电解产生的微泡运动的图像测量。我们发现气泡与涡激流动之间的对流相互作用,即,由电极附近的密度差异引起的瑞利-泰勒不稳定性会引起反向旋转的涡流,这些涡流会加速气泡并使它们沿着它们之间引起的流动路径对齐,从而导致上升速度的增加及其在统计平衡状态中的变化。我们在我们提出的经验模型中描述了这种群体中气泡上升的统计特征,并推导出其最佳参数。我们预计我们的发现将成为理解与目前电解产生的微气泡具有类似尺寸分布的海洋气泡行为的起点。导致上升速度的增加及其在统计平衡状态下的变化。我们在我们提出的经验模型中描述了这种群体中气泡上升的统计特征,并推导出其最佳参数。我们预计我们的发现将成为理解与目前电解产生的微气泡具有类似尺寸分布的海洋气泡行为的起点。导致上升速度的增加及其在统计平衡状态下的变化。我们在我们提出的经验模型中描述了这种群体中气泡上升的统计特征,并推导出其最佳参数。我们预计我们的发现将成为理解与目前电解产生的微气泡具有类似尺寸分布的海洋气泡行为的起点。
更新日期:2021-03-01
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