Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session F08: Bubbles: Dynamics III |
Hide Abstracts |
Chair: Shu Takagi, University of Tokyo Room: Georgia World Congress Center B213 |
Monday, November 19, 2018 8:00AM - 8:13AM |
F08.00001: Gravity wave in a glass of Guinness beer Tomoaki Watamura, Kazuyasu Sugiyama, Kenichiro Yamamoto, Yuko Yotsumoto, Takashi Shiono To address an open problem how the bubble texture forms in a glass of Guinness beer, we investigated the propagation velocity of texture and individual bubble velocity by means of high speed microscope imaging. We inferred the liquid phase velocity from the observation of bubbles motion. As the result of measurements, we found that the texture formation at the Froude number, defined by the liquid phase velocity and the bubble-free layer thickness, Fr > 1 is excellent accord with the onset of primary instability of the falling liquid film. Our experimental observation suggests that the gravity wave of the stratified flow is responsible to the texture-formation of Guinness beer. |
Monday, November 19, 2018 8:13AM - 8:26AM |
F08.00002: Looking under the skirt of a bubble Dominique Legendre For viscous liquids and large bubble, a thin layer of fluid, commonly referred to as a “skirt”, can be observed issuing from the rim of bubbles. First reported for drops by Thomson and Newall (1885), the appearance of skirts requires a sufficiently viscous continuous phase. A criterion for the skirt formation can be obtained considering that the balance between the surface tension contribution and the normal viscous stress becomes impossible (Bhaga 1976). Different theories have been proposed for the skirt thickness (Guthrie and Bradshaw 1969, Wairegi 1974, Ray & Properetti 2014). The significant differences between experimental observations and proposed theories have motivated this work. We present direct numerical simulations of skirt bubble and investigate in detail the flow field in the skirt in order to discuss the skirt formation and the assumptions made in the theoretical derivations. Our results confirm that the flow can be considered as parallel in the skirt and that the velocity on the inner side is much smaller than the bubble velocity in agreement with Wairegi’s measurements. The simulations also outlines that the liquid velocity on the outer side of the skirt differs from the bubble rising velocity resulting in a reduction of the skirt thickness. |
Monday, November 19, 2018 8:26AM - 8:39AM |
F08.00003: How to stop a serial bubbling? Quentin Magdelaine, Alban Sauret, Frédéric Mondiot, Jérémie Teisseire, Arnaud Antkowiak Generating bubbles by injecting air slowly with a syringe in a quiescent liquid is a standard process. However, the experiment shows that the generation of a single bubble can be a challenge as a train of bubbles is often observed even at very slow injection rate. Here, we explore the different regimes of bubble generation experimentally. We also model the situation through direct numerical simulations, which reproduce and extend the experimental measurements. We rationalize the observation of the serial bubbling with a thermodynamic model and highlight the different regimes. The serial bubbling can be a problem in some applications, but its understanding can also be leveraged to deliver a given number of bubbles. |
Monday, November 19, 2018 8:39AM - 8:52AM |
F08.00004: Regimes of bubble suction from a needle submerged in a very viscous liquid Daniel Moreno-Boza, Mariano Rubio-Rubio, Javier Rivero-Rodriguez, Alejandro Sevilla The contraction dynamics of a static pendant bubble pinned at the edge of a needle and immersed in a quiescent viscous liquid is investigated by means of numerical simulations at constant suction flow rate in the Stokes limit. Through a systematic parametric study we aim at establishing the critical conditions for the formation of satellite bubbles in the parametric space spanned by the three relevant parameters of the problem, namely the Bond number, the capillary number and the dimensionless initial volume. An experimental study is under way to verify the numerical findings. |
Monday, November 19, 2018 8:52AM - 9:05AM |
F08.00005: Collision of air bubble with parallel arranged fibers Ryeol Park, Wonjung Kim We present a combined experimental and theoretical study of bubble impact on parallel arranged fibers. Using high-speed videography, we experimentally observed bubble collisions on a fiber array under various conditions. The experiments showed that the collision outcomes can be classified into three modes of capturing, single bubble rising, and splitting. Through a scale analysis, we explain how mode selection depends primarily on the collision speed of bubbles and inter-fiber distance. We also found that in the splitting mode, the size of daughter bubbles cannot be easily controlled due to the dependency on the eccentricity. Our results provide insights into the design of mesh structures that are widely used to control bubbles in fluid transfer systems. |
Monday, November 19, 2018 9:05AM - 9:18AM |
F08.00006: Detachment Dynamics Induced by Unequal Microbubble Coalescence Rou Chen, Likun Zhu, Huidan (Whitney) Yu Understanding the dynamics of microbubble detachment is critical in various engineering systems, such as the design of micro gas generator to reduce the inefficiency of reaction, self-cleaning in the microchannel, and thermal management of semiconductor products, to name a few. In this work, we numerically study the behavior of coalescence-induced detachment of unequal size microbubbles on a flat rigid wall using a free-energy approach based on lattice Boltzmann method. The reliability of the triple-phase (solid, liquid, and gas) lattice Boltzmann model is validated through comparisons with analytical and experimental results of bubble coalescence on the solid surface. From systematic simulation and analysis by varying the bubble size ratio, contact angle, and height of the channel, we reveal the detachment mechanics induced by unequal microbubble coalescence and seek for an optimal design to detach bubbles in micro-channel. It is found that the detachment of the bubble is easier to occur when the solid phase with super hydrophilic material and the bubble size ratio is close to 1. |
Monday, November 19, 2018 9:18AM - 9:31AM |
F08.00007: Abstract Withdrawn
|
Monday, November 19, 2018 9:31AM - 9:44AM |
F08.00008: Fluid Mechanics of Gas Jets and Vortex Rings Released from Bursting Bubbles Ali Ahmad Al Dasouqi, David W Murphy Bubble bursting is important in ocean-atmosphere processes (e.g. marine aerosol formation), food science (e.g. champagne), and industrial processes (e.g. gas fluxing of molten metal to remove impurities). The fluid mechanics of the liquid component of bubble bursting, including film cap retraction and droplet formation, has been well studied. In contrast, the fluid mechanics of the pressurized gas released from a bursting bubble has not been well investigated, but this flow may influence the mixing of released gas and the spatial distribution of generated droplets. Here we investigate the gas flow released from the bursting of smoke-filled bubbles floating at an air-liquid interface using high speed visualization at 10 kHz. For air-water bubbles of 3.5 cm diameter, the ruptured bubble cap releases a jet with a speed of 4.6 m/s through the expanding hole in the bubble film. The jet rolls up into a vortex ring which may travel tens of bubble diameters. Jet speed decreases linearly with size to approximately 1.6 m/s for an 0.5 mm diameter bubble. Jet speed decreases for similarly sized bubbles in more viscous liquids. Using dimensional analysis, we compare the effects of surface tension, viscosity, and bubble size on gas jet speed and vortex ring characteristics for various liquids. |
Monday, November 19, 2018 9:44AM - 9:57AM |
F08.00009: Optical visualization of ultrasonic cavitation bubbles near an oil-deposited glass surface Kentaro Asano, Keita Ando Low-frequency underwater ultrasound is conventionally used to degrease metallic parts. It is important to reveal its cleaning mechanism in order to achieve more efficient cleaning for practical purposes. In this study, we set up a simple ultrasonic cleaning test and optically visualize ultrasonic cavitation bubbles. Glass plates on which an oil drop is deposited are used as a cleaning sample. The sample is soaked in a water container and subjected to 28-kHz underwater ultrasound. The ultrasound-induced cavitation bubbles near the glass surface are recorded by a high-speed camera. It is observed that cavitation bubbles nucleate preferentially in the water (not in the oil) and subsequently penetrate into the oil, perhaps, due to Bjerknes force. In the presentation, we will report on the complex dynamics of bubbles in the oil and their role in degreasing. |
Monday, November 19, 2018 9:57AM - 10:10AM |
F08.00010: Bubble-induced fluid stresses and viability changes in nearby mammalian cells Oliver McRae, James C Bird A living cell, when subjected to a high fluid stress, can have key biological processes disrupted, potentially leading to cell death. In the biotechnology industry the mammalian CHO cell is grown in aerated tanks where locally elevated stresses - created by bubbles rapidly deforming during rupture, coalescence, or pinch-off - can be high enough to kill nearby cells; however the effect of elevated stresses on cells at the timescales of these bubble events is unclear. Here we investigate the effect on cell viability from fluid stresses created by a bubble undergoing topological change, using a combination of computational fluid dynamics (CFD), numerical particle tracking, and microfluidics. CFD and particle tracking are employed to unlock the stress field history in the fluid surrounding a deforming bubble. In a microfluidic device CHO cells are injected near to a rapidly rearranging bubble, with the cell's motion captured using high-speed optical microscopy. Using this approach, we predict mortality on a cell-by-cell basis, eliciting an overall bubble-induced effect on a cell population's viability. We believe this work will be especially pertinent in the biotechnology sector, guiding bioreactor design and the optimization of cell culture protocols. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700