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© 2016 AIP Publishing LLC. The present paper focuses on the simulation of the expansion and aspherical collapse of a laser-generated bubble subjected to an acceleration field and comparison of the results with instances from high-speed videos. The interaction of the liquid and gas is handled with the volume of fluid method. Compressibility effects have been included for each phase to predict the propagation of pressure waves. Initial conditions were estimated through the Rayleigh Plesset equation, based on the maximum bubble size and collapse time. The simulation predictions indicate that during the expansion the bubble shape is very close to spherical. On the other hand, during the collapse the bubble point closest to the bottom of the container develops a slightly higher collapse velocity than the rest of the bubble surface. Over time, this causes momentum focusing and leads to a positive feedback mechanism that amplifies the collapse locally. At the latest collapse stages, a jet is formed at the axis of symmetry, with opposite direction to the acceleration vector, reaching velocities of even 300 m/s. The simulation results agree with the observed bubble evolution and pattern from the experiments, obtained using high speed imaging, showing the collapse mechanism in great detail and clarity.
|Additional Information:||This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in P. Koukouvinis, M. Gavaises, O. Supponen and M. Farhat (2016) Numerical simulation of a collapsing bubble subject to gravity, Physics of Fluids 28, and may be found at http://dx.doi.org/10.1063/1.4944561|
|Subjects:||T Technology > TJ Mechanical engineering and machinery|
|Divisions:||School of Engineering & Mathematical Sciences > Engineering|
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