Bulletin of the American Physical Society
75th Annual Meeting of the Division of Fluid Dynamics
Volume 67, Number 19
Sunday–Tuesday, November 20–22, 2022; Indiana Convention Center, Indianapolis, Indiana.
Session L09: Bubbles: Dynamics and Rupture I |
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Chair: Jie Feng, University of Illinois at Urbana-Champai Room: 136 |
Monday, November 21, 2022 8:00AM - 8:13AM |
L09.00001: Singular jets produced by oil-coated bubble bursting Jie Feng, Zhengyu Yang, Bingqiang Ji, Jesse T Ault Surface bubbles are ubiquitous in many natural and engineering processes, and bubble bursting aerosols are of particular interest because of their critical role in mass and momentum transfer across interfaces\ All prior studies claim that bursting of a millimeter-sized bare bubble at an aqueous surface produces jet drops with a typical size of O(100 μm), much larger than film drops of O(1 μm) from the disintegration of a bubble cap. Here, we document the hitherto unknown phenomenon that jet drops can be as small as a few microns when the bursting bubble is coated by a thin oil layer. We provide evidence that the faster and smaller jet drops result from the singular dynamics of the oil-coated cavity collapse. The unique air-oil-water compound interface offers a distinct damping mechanism to smooth out the precursor capillary waves during cavity collapse, leading to a more efficient focusing of the dominant wave and thus allowing singular jets over a much wider parameter space beyond that of a bare bubble. We further identify and rationalize the hydrodynamic conditions for the singular jet regime regarding the oil viscosity and coating fraction. As such contaminated bubbles are widely observed, the previously unrecognized fast and small jet drops may largely enhance bubble-driven flux across the interface, contributing to the aerosolization and long-range transport of any bulk substances. |
Monday, November 21, 2022 8:13AM - 8:26AM |
L09.00002: Low-cost modelling for bubble collapse displacement Elijah Andrews, Ivo R Peters A gas or vapor bubble collapsing in the vicinity of a rigid boundary displaces towards the boundary and produces a high-speed jet directed at the boundary. We present a low-cost model that can be used to predict the direction and distance of bubble displacement in complex geometries. This model uses the Boundary Element method to predict the geometric 'anisotropy' experienced by the bubble. We experimentally explore a robust measure of bubble displacement, showing that the bubble displacement in a series of different complex geometries behaves as a single function of the predicted anisotropy parameter values. |
Monday, November 21, 2022 8:26AM - 8:39AM |
L09.00003: Understanding and modeling the internal dynamics of an interface in reference to bubble dynamics Joseph Thalakkottor Gibbs was the first to represent a phase interface by a dividing surface. Here, we extend Gibbs' concept of dividing surface to encompass fluid fronts such as a material or phase interface, shock front, and contact line. This extension of Gibbs' dividng surface is defined as a mathematical hypersurface that has its own material properties and internal dynamics. This is different from the usual way of describing a fluid front as a mathematical boundary with no mass and hence, no dynamics. This fact allows it to be both kinematically and dynamically equivalent to the physical interface, thereby providing a more accurate representation. Here, we use the canonical example of bubble growth and collapse to highlight this difference and show the importance of accounting for the mass of the interface. |
Monday, November 21, 2022 8:39AM - 8:52AM |
L09.00004: Everlasting bubbles and liquid films Michael Baudoin, Aymeric Roux, Alexis Duchesne Soap bubbles are by essence of fragile and ephemeral nature. Depending on the composition of their liquid shell and their environment, bubbles bursting can be triggered by the drainage of the liquid induced by gravity and/or the evaporation of the liquid and/or the presence of nuclei locally affecting the shell. In this paper, we design bubbles made of a composite liquid interface able to neutralize all these effects and hence keep their integrity in a standard atmosphere. This composite shell is obtained by addition of glycerol to water, whose hygroscopicity counterbalances water evaporation and of jammed particles limiting the drainage and protecting the bubbles. Their evolution toward a stable state is rationalized with a nonlinear model able to predict their evolution as a function of the initial water/glycerol content and the surrounding atmosphere humidity. In addition to providing a fascinating object for researchers, this work unveils a composite liquid material with unique robustness, which can easily be manufactured to design complex objects. |
Monday, November 21, 2022 8:52AM - 9:05AM |
L09.00005: How evaporative cooling can stabilize a large bubble James Bird, Mark Menesses, Laurent Royon, Matthieu Roche Bubbles at a liquid surface are ephemeral and are expected to thin and pop. However, if the bubble is sufficiently volatile, evaporative cooling can counteract the drainage. Here we demonstrate that for a range of liquids, evaporative cooling can be large enough to reverse the direction of drainage, thus preventing breakup over significant timescales. Through systematic experiments and theoretical modeling, we explore the conditions needed for large bubble films to spontaneously reverse their drainage. Surprisingly, bubbles in liquids that evaporate as quickly as water demonstrate this phenomenon, raising the question "why are we not surrounded by an ocean of foam?" |
Monday, November 21, 2022 9:05AM - 9:18AM |
L09.00006: Experimental observation of a confined bubble moving in shear-thinning fluids SungGyu Chun, Jie Feng When a confined bubble translates in a cylindrical capillary tube, a thin film of liquid separates the bubble surface and the tube inner wall, with its thickness determined by the interplay of viscous, inertial and capillary effects. Although the dynamics of a bubble in a Newtonian liquid has been the subject of several studies since the pioneering works of Taylor and Bretherton, the case where the fluid exhibits a non-Newtonian behavior is not much understood. In applcations such as enhanced oil recovery and drug delivery, the fluids are likely to exhibit non-Newtonian properties. In this work, we consider the classical Bretherton problem with non-Newtonian fluids. We provide quantitative measurement of the thickness of deposited liquid film for carboxymethyl cellulose (CMC) and Carbopols solutions with different concentrations in a wide range of Capillary numbers. We further compare our investigations with the scaling law considering the effecitve viscosity to extend the classical Bretherton's correlations non-Newtonian fluids. Our results may enrich the fundamental understanding of the multi-phase flows involving non-Newtonian fluids. |
Monday, November 21, 2022 9:18AM - 9:31AM |
L09.00007: Dynamics of air bubbles in removing proteins or bacteria on a tilted surface Alireza Hooshanginejad, Timothy Sheppard, Purui Xu, Janeth Manyalla, John Jaicks, Ehsan Esmaili, Sunghwan Jung In this study, we conduct experiments to test the cleaning efficacy of bubbles at different inclination angles of a surface. We use two different surfaces coatings of either a protein solution or a bacterial biofilm. Our experimental results indicate that bubbles exhibit the best cleaning efficacy at the surface angle of θ=20o for polydisperse bubbles in the range of 0.3-2 mm and with an average radius of 0.6 mm in radius. To gain a better understanding of the underlying mechanism, we perform numerical analysis of a single air bubble impacting surfaces with different angles. Our numerical and theoretical results show that the shear stress, that is proportional to the sliding speed but inversely proportional to the film thickness, result in the maximum shear force occurring at θ≈22o ≈π/8 in good agreement with the experiments. |
Monday, November 21, 2022 9:31AM - 9:44AM |
L09.00008: Deformation and break-up of a bubble in a horizontal solid-body rotation flow Majid Rodgar, Hélène Scolan, Jean-Louis Marié, Delphine Doppler, Jean-Philippe Matas We study the dynamics of a bubble released inside a horizontal |
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