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 E11: Bubbles: Cavitation II |
Hide Abstracts |
Chair: Eric Johnsen, University of Michigan Room: Georgia World Congress Center B216 |
Sunday, November 18, 2018 5:10PM - 5:23PM |
E11.00001: Inkophobic particles trigger nozzle failure: bubble nucleation, dynamics, and diffusive growth visualized in a MEMS-based piezo-acoustic printhead Tim Segers, Arjan Fraters, Marc van den Berg, Youri de Loore, Hans Reinten, Herman Wijshoff, Michel Versluis, Detlef Lohse The stability of piezo drop-on-demand inkjet printing is compromised through the stochastic entrainment of bubbles inside the ink channel. Here, bubble nucleation, translation, and growth in a micro-electro-mechanical printhead was studied using high-speed imaging triggered by changes in ink channel acoustics. It was found that inkophobic dirt particles trigger bubble nucleation upon their interaction with the oscillating meniscus. The jet length increase after bubble nucleation was shown to be a result of the bubble-induced decrease of the channel resonance frequency. Channel pressure profiles were measured from a fit of the measured radial bubble dynamics to the Rayleigh-Plesset equation. The acoustically driven bubble translates towards the ink channel wall due to acoustic radiation forces and convective ink flow. The ink velocity field was characterized using particle-tracking-velocimetry. The vortex flow above the oscillating meniscus was shown to trap dirt particles thereby increasing the particle-meniscus interaction probability. |
Sunday, November 18, 2018 5:23PM - 5:36PM |
E11.00002: Scaling laws of top jet drop size and speed from bubble bursting including gravity and inviscid limit Alfonso M Ganan-Calvo Jet droplets from bubble bursting are determined by a limited parametrical space: the liquid properties (surface tension σ, viscosity μ, and density ρ), mother bubble size Ro and acceleration of gravity g (i.e. 5 dimensional parameters). A detailed physical description of the ejection process to model both the ejected droplet radius R and its initial launch speed V is provided, leading to a scaling law including both resulting parameters from dimensional analysis: the Ohnesorge and Bond numbers (Oh and Bo). Two limits are identified for Oh: one (Oh1=0.038) is the critical value above which no droplet ejection takes place, and the other (Oh2=0.0045) is a new critical value which signals when viscous effects vanish. Gravity effects are consistently introduced from energy conservation principles. The proposed scaling law produces an extraordinary collapse of all published experimental measurements collected for both the ejected droplet radius and ejection speed. |
Sunday, November 18, 2018 5:36PM - 5:49PM |
E11.00003: Capillary waves after bubble coalescence and their role in the generation of bubble bursting jets Jose M Gordillo, Javier Rodriguez-Rodriguez Here we provide a theoretical framework describing the generation and subsequent breakup of the fast and vertical Worthington jet ejected out of the liquid when a bubble of radius R, initially at rest at an interface, bursts. The correct scalings for the diameters and the velocities of the drops emitted from the highly stretched jet tip, in the limit of negligible gravitational effects, are deduced taking into account the experimental observation that the dynamics of the jet ejection process is governed by the traveling wave excited during the capillary retraction of the rim bordering the bubble cap. The self-consistent physical mechanism presented here explains the emergence of the vertical jet as a consequence of the breakup of the self-similarity of the inertio-capillary cavity collapse caused by the waves excited during the rim retraction process, which possess a characteristic wavelength proportional to ROh1/2, with Oh=μ/(ρRσ)1/2 the Ohnesorge number and where ρ, μ and σ indicate the liquid density, viscosity and interfacial tension coefficient, respectively. |
Sunday, November 18, 2018 5:49PM - 6:02PM |
E11.00004: Coalescence Dynamics of a Hollow Drop Kirti Sahu, Hiranya Deka, Gautam Biswas When a drop (Fluid 1) falls through another fluid (Fluid 2) to eventually hit a pool of the same liquid (Fluid 1), after coalescence, the drop may produce a daughter drop by draining some liquid into the pool. This phenomenon of forming daughter drops of smaller volumes is called partial coalescence. Although satellite drop formation has been widely studied for the case of a drop coalescing in a liquid pool, the satellite formation during the coalescence of a hollow drop has remained unexplored. We have performed comprehensive numerical investigations using Coupled Level Set and Volume of Fluid (CLSVOF) method to unveil the mechanism of partial coalescence of a hollow drop on a liquid pool. The coalescence phenomenon depends on the volume of the bubble inside the drop which is analyzed in terms of the inner diameter to the outer diameter ratio of the drop. There exists a critical diameter ratio above which partial coalescence is inhibited. Moreover, the break-up of the drop is also observed depending on its diameter ratio. We have explored the critical values of appropriate non-dimensional parameters for which transition from partial to complete coalescence occurs. |
Sunday, November 18, 2018 6:02PM - 6:15PM |
E11.00005: Nucleation, bubble growth and coalescence Victoria Pereira, Andrew Fowler In gas-liquid two-phase pipe flows, flow regime transition is associated with changes in the micro-scale geometry of the flow. In particular, the bubbly-slug transition is associated with the coalescence and break-up of bubbles in a turbulent pipe flow. We consider a sequence of models designed to facilitate an understanding of this process. The simplest such model is a classical coalescence model in one spatial dimension. This is formulated as a stochastic process involving nucleation and subsequent growth of ‘seeds’, which coalesce as they grow. In a development of this, we allow for bubble fragmentation, and we study the evolution of the bubble size distribution both analytically and numerically. We also present some ideas concerning ways in which the model can be extended to more realistic two- and three-dimensional geometries. |
Sunday, November 18, 2018 6:15PM - 6:28PM |
E11.00006: Density functional study on bubble nucleation in liquid hydrogen as a quantum fluid Shin-ichi Tsuda, Daiki Yasui, Satoshi Watanabe, Hiroki Nagashima, Takashi Tokumasu Bubble nucleation in a classical fluid such as liquid argon or standard Lennard-Jones fluid has been widely studied using classical nucleation theory (CNT), density functional theory (DFT), some statistical mechanical approaches, or molecular simulations. However, that of quantum fluid such as liquid hydrogen or liquid helium has hardly been studied from a molecular point of view, compared with classical fluid without quantum nature. In this study, we employed a phenomenological DFT, which is based on an equation of state (EOS) of liquid hydrogen, and evaluated the energy barrier height in the bubble nucleation. Also, we applied the same kind of DFT to classical liquid hydrogen without quantum nature, whose DFT is based on an EOS for standard Lennard-Jones fluid. As a result, the nucleation barrier in liquid hydrogen shows a similar tendency to that in classical hydrogen if those barriers are compared at the same temperature reduced by critical temperature and the same reduced superheat ratio, which is defined by the chemical potential at the saturation point and that at the spinodal. It shows that a principle of corresponding state for energy barrier in bubble nucleation may be satisfied between quantum fluid and classical fluid, which is a new insight in this field. |
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