arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2002.02261physics.flu-dyn
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具有高度非球形特征的大尺度气枪气泡动力学模型

Modelling large scale airgun-bubble dynamics with highly non-spherical features

Shuai Li, Devaraj van der Meer, A-Man Zhang, Andrea Prosperetti, Detlef Lohse

摘要:

深入了解米级气枪气泡的动力学特性对海底地球物理勘探具有重要意义。在这项研究中,我们使用边界积分方法来研究高度非球形气枪气泡动力学及其相应的压力波发射。此外,提出了一个模型,也考虑了空气从气枪端口,这是最关键的因素,以估计压力波的初始峰值的释放过程。数值模拟显示出良好的协议与实验,在非球形气泡的形状和压力波。此后,端口打开时间$T\rm_{open}$,气枪射击深度,传热和重力的影响进行了数值研究。我们发现,一个较小的$T\rm_{open}$导致更猛烈的空气释放,从而导致更强的高频压力波发射,然而,低频压力波的影响很小。此外,非球形气泡动力学高度依赖于弗劳德数$Fr$。从$Fr=2$开始,随着$Fr$增加,射流包含较低的动能,导致气泡破裂本身的较强能量聚焦,从而在气泡破裂阶段期间产生较大的压力峰值。对于$Fr \ge 7$,球形气泡理论成为气枪气泡的适当描述。本研究之新发现,可为未来气枪之实际操作及环保型气枪设计提供参考。

英文摘要:

A thorough understanding of the dynamics of meter-sized airgun-bubbles is very crucial to seabed geophysical exploration. In this study, we use the boundary integral method to investigate the highly non-spherical airgun-bubble dynamics and its corresponding pressure wave emission. Moreover, a model is proposed to also consider the process of air release from the airgun port, which is found to be the most crucial factor to estimate the initial peak of the pressure wave. The numerical simulations show good agreement with experiments, in terms of non-spherical bubble shapes and pressure waves. Thereafter, the effects of the port opening time $T\rm_{open}$, airgun firing depth, heat transfer, and gravity are numerically investigated. We find that a smaller $T\rm_{open}$ leads to a more violent air release that consequently causes stronger high-frequency pressure wave emissions; however, the low-frequency pressure waves are little affected. Additionally, the non-spherical bubble dynamics is highly dependent on the Froude number $Fr$. Starting from $Fr=2$, as $Fr$ increases, the jet contains lower kinetic energy, resulting in a stronger energy focusing of the bubble collapse itself and thus a larger pressure peak during the bubble collapse phase. For $Fr \ge 7$, the spherical bubble theory becomes an appropriate description of the airgun-bubble. The new findings of this study may provide a reference for practical operations and designing environmentally friendly airguns in the near future.

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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