Bursting bubbles and the formation of gas jets and vortex rings
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RESEARCH ARTICLE
Bursting bubbles and the formation of gas jets and vortex rings Ali A. Dasouqi1 · Geum‑Su Yeom2 · David W. Murphy1 Received: 22 July 2020 / Revised: 21 October 2020 / Accepted: 23 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Bubble bursting is important in air–sea interactions, food science, and industry, but the process of the pressurized gas escaping from inside the bursting bubble is not well understood. The fluid dynamics of gas jets and vortex rings produced by the bursting of 440 µm to 4 cm diameter smoke-filled bubbles resting at an air–water interface is investigated using high-speed stereophotogrammetry. The initial speed of the gas jet released from the bubbles increases with parent bubble size until the Bond number reaches unity and subsequently increases more slowly. The slow, low Reynolds number jets characteristic of small bubbles are attributed to high film retraction speeds which produce relatively large holes in the bubble cap, and these jets roll up into spherical, slow-growing vortex rings which travel short distances. However, the low film retraction speeds characteristic of larger bubbles produce high speed, high Reynolds number jets emitted through relatively small holes which roll up into highly oblate, fast-growing, far-traveling vortex rings. The tiniest bubbles eject only a thin stem-like jet which does not form a vortex ring. Finally, a simple scaling relationship relating the gas jet Reynolds number to the square root of the parent bubble Bond number is proposed. Graphic abstract
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* David W. Murphy [email protected] 1
Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620, USA
Department of Mechanical Engineering, Kunsan National University, Gunsan 54150, Republic of Korea
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Bubbles are ubiquitous in industrial and environmental processes, and bubble bursting is a widely studied and highly important physical process. MacIntyre (1972) estimated that 1018–1020 bubbles burst every second on the ocean surface, and the tiny marine aerosol droplets ejected into the atmosphere through bursting have a significant impact on climate processes including cloud formation and precipitation (Mason 1957; Blanchard 1963). In addition, marine
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aerosol droplets ejected from bursting bubbles significantly contribute to the exchange and circulation of organic and chemical materials between water bodies and the atmosphere (Lewis and Schwartz 2004). These droplets also may present a respiratory health risk as they may carry brevetoxins from algal blooms or crude oil and chemical dispersants from oil spills (Cheng et al. 2005; Prather et al. 2013; Ehrenhauser et al. 2014; Murphy et al. 2015). Many industrial applications, including gas fluxing and copper electrowinning, also involve bubble bursting in which the release of hazardous aerosols and gases needs to be controlled (Fjeld 2006; Zhang et al. 2011; Al Shakarji et al. 2012; Mortensen et al. 2017). In
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