Bulletin of the American Physical Society
69th Annual Meeting of the APS Division of Fluid Dynamics
Volume 61, Number 20
Sunday–Tuesday, November 20–22, 2016; Portland, Oregon
Session E21: Bubbles: Cavitation, Collapse |
Hide Abstracts |
Chair: Eric Johnsen, University of Michigan Room: D139-140 |
Sunday, November 20, 2016 5:37PM - 5:50PM |
E21.00001: Simulations of Shock-induced Bubble Collapse near Hard and Soft Objects Mauro Rodriguez, Eric Johnsen Understanding the dynamics of cavitation bubbles and shock waves in and near hard and soft objects is important particularly in various naval and medical applications. Two examples are therapeutic ultrasound procedures, which utilize this phenomenon for breaking kidney stones (lithotripsy) and ablation of pathogenic tissue (histotripsy), and erosion to elastomeric coatings on propellers. Although not fully understood, the damage mechanism combines the effect of the incoming pulses and cavitation produced by the high tension of the pulses. To understand the damage mechanism, it is of key interest to quantifying the influence of the shock waves on the material and the response of the material to the shock waves. A novel Eulerian numerical approach for simulating shock and acoustic wave propagation in viscoelastic media is leveraged to understand this influence. High-fidelity simulations of the bubble collapse dynamics for various experimental configurations (i.e. the viscous or viscoelastic material surrounding the bubble and neighboring object's rigidity are varied) will be conducted. In particular, we will discuss the shock emission from collapse and its propagation in the neighboring object, including stresses thereby produced. [Preview Abstract] |
Sunday, November 20, 2016 5:50PM - 6:03PM |
E21.00002: The effects of bubble-bubble interactions on pressures and temperatures produced by bubbles collapsing near a rigid surface Shahaboddin Alahyari Beig, Eric Johnsen Cavitation occurs in a wide range of hydraulic applications, and one of its most important consequences is structural damage to neighboring surfaces following repeated bubble collapse. A number of studies have been conducted to predict the pressures produced by the collapse of a single bubble. However, the collapse of multiple bubbles is known to lead to enhanced collapse pressures. In this study, we quantify the effects of bubble-bubble interactions on the bubble dynamics and pressures/temperatures produced by the collapse of a pair of bubbles near a rigid surface. For this purpose, we use an in-house, high-order accurate shock- and interface-capturing method to solve the 3D compressible Navier-Stokes equations for gas/liquid flows. The non-spherical bubble dynamics are investigated and the subsequent pressure and temperature fields are characterized based on the relevant parameters entering the problem: stand-off distance, geometrical configuation, collapse strength. We demonstrate that bubble-bubble interactions amplify/reduce pressures and temperatures produced at the collapse, and increase the non-sphericity of the bubbles and the collapse time, depending on the flow parameters. [Preview Abstract] |
Sunday, November 20, 2016 6:03PM - 6:16PM |
E21.00003: Uniting the family of jets of single cavitation bubbles Outi Supponen, Danail Obreschkow, Marc Tinguely, Philippe Kobel, Nicolas Dorsaz, Mohamed Farhat Micro-jets are high-speed liquid jets that are produced when a cavitation bubble experiences a non-spherical collapse. Such jets may be driven by any anisotropy in the liquid, such as those induced by near surfaces, gravity, pressure gradients in flows or shock waves. Here we unify this diverse family of micro-jets by describing their dynamics with a single anisotropy parameter $\zeta\ge0$ that represents a dimensionless version of the liquid momentum at the collapse point. We observe, experimentally and numerically, that the dimensionless jet parameters describing the jet speed, jet impact time, bubble displacement, bubble volume at jet impact and vapor-jet volume, all reduce to functions of $\zeta$. Consequently, a measurement of a single parameter, such as the bubble displacement, may be used to estimate any other parameter, such as the jet speed. The jets are phenomenologically categorized into three visually distinct regimes: weak jets that hardly pierce the bubble, intermediate jets that pierce the bubble late during the collapse, and strong jets that pierce the bubble at an early stage of the collapse. In the weak and intermediate jet regimes, that is, when $\zeta<0.1$, the dimensionless jet parameters scale as simple power laws of $\zeta$ independently of the jet driver. [Preview Abstract] |
Sunday, November 20, 2016 6:16PM - 6:29PM |
E21.00004: Dynamics of a vapor nanobubble collapsing near a solid boundary Carlo Massimo Casciola, Francesco Magaletti, Mirko Gallo, Giorgia Sinibaldi, Luca Marino The collapse of a nano-bubble near a solid wall is addressed exploiting a phase field model (Magaletti et al., Phys. Rev. Lett. 2015). The dynamics, triggered by a shock wave in the liquid, is explored for different conditions. It is characterized by a sequence of collapses and rebounds of the pure vapor bubble accompanied by the emission of shock waves in the liquid. The shocks are reflected by the wall to impinge back on the re-expanding bubble. The presence of the wall and the impinging shock wave break the symmetry of the system, leading, for sufficiently strong intensity of the incoming shock wave, to the poration of the bubble and the formation of an annular structure and a liquid jet Intense peaks of pressure and temperatures are found also at the wall, confirming that the strong localized loading combined with the jet impinging the wall is a potential source of substrate damage induced by the cavitation (Magaletti et al., J. Multiphase Flows 2016). Comparison of the numerical results with recent experiments on the collapse of a Laser induced cavitation bubble will also be discussed. [Preview Abstract] |
Sunday, November 20, 2016 6:29PM - 6:42PM |
E21.00005: Ultrafast cavitation induced by an X-ray laser in water drops Claudiu Stan, Philip Willmott, Howard Stone, Jason Koglin, Mengning Liang, Andrew Aquila, Joseph Robinson, Karl Gumerlock, Gabriel Blaj, Raymond Sierra, Sebastien Boutet, Serge Guillet, Robin Curtis, Sharon Vetter, Henrik Loos, James Turner, Franz-Josef Decker Cavitation in pure water is determined by an intrinsic heterogeneous cavitation mechanism, which prevents in general the experimental generation of large tensions (negative pressures) in bulk liquid water. We developed an ultrafast decompression technique, based on the reflection of shock waves generated by an X-ray laser inside liquid drops, to stretch liquids to large negative pressures in a few nanoseconds. Using this method, we observed cavitation in liquid water at pressures below -100 MPa. These large tensions exceed significantly those achieved previously, mainly due to the ultrafast decompression. The decompression induced by shock waves generated by an X-ray laser is rapid enough to continue to stretch the liquid phase after the heterogeneous cavitation occurs in water, despite the rapid growth of cavitation nanobubbles. We developed a nucleation-and-growth hydrodynamic cavitation model that explains our results and estimates the concentration of heterogeneous cavitation nuclei in water. [Preview Abstract] |
Sunday, November 20, 2016 6:42PM - 6:55PM |
E21.00006: Bursting of a bubble confined in between two plates Mayuko Murano, Natsuki Kimoto, Ko Okumura Rupture of liquid thin films, driven by surface tension, has been studied for more than a century [1,2]. As for a three-dimensional film, it is reported theoretically and numerically that the film edge, regardless of its viscosity, eventually attains the Taylor-Culick velocity predicted on the basis of inviscid theory [3]. Here, we studied the bursting of films in confined geometries. The confined film bursts at a speed three to five orders of magnitude slower, which means that the bursting dynamics is completely different from that of three dimensional films. We quantify the shape of rims and velocity field inside the film via strongly magnified high-speed images of bursting tips, and provide physical insights on the bursting dynamics by using a simple model. Under a certain condition, the confined film bursts like a three-dimensional film. We will also discuss the transition of the bursting dynamics from three-dimensional to confined one. [1] L. Rayleigh, Nature 44 (1891) [2] F. E. Culick, J. Appl. Phys. 31 (1960) [3] N. Savva and J. W. M. Bush, J. Fluid Mech. 626 (2009) [Preview Abstract] |
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