title: Effect of static pressure on acoustic energy radiated by cavitation bubbles in viscous liquids under ultrasound.
abstract: The effect of static pressure on acoustic emissions including shock-wave emissions from cavitation bubbles in viscous liquids under ultrasound has been studied by numerical simulations in order to investigate the effect of static pressure on dispersion of nano-particles in liquids by ultrasound. The results of the numerical simulations for bubbles of 5 μm in equilibrium radius at 20 kHz have indicated that the optimal static pressure which maximizes the energy of acoustic waves radiated by a bubble per acoustic cycle increases as the acoustic pressure amplitude increases or the viscosity of the solution decreases. It qualitatively agrees with the experimental results by Sauter et al. [Ultrason. Sonochem. 15, 517 (2008)]. In liquids with relatively high viscosity (∼200 mPa s), a bubble collapses more violently than in pure water when the acoustic pressure amplitude is relatively large (∼20 bar). In a mixture of bubbles of different equilibrium radius (3 and 5 μm), the acoustic energy radiated by a 5 μm bubble is much larger than that by a 3 μm bubble due to the interaction with bubbles of different equilibrium radius. The acoustic energy radiated by a 5 μm bubble is substantially increased by the interaction with 3 μm bubbles.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan. k.yasui@aist.go.jp
authors.forename: Kyuichi
authors.initials: K
authors.lastname: Yasui
authors.forename: Atsuya
authors.initials: A
authors.lastname: Towata
authors.forename: Toru
authors.initials: T
authors.lastname: Tuziuti
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Kozuka
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kato
mesh_terms: D003198:Computer Simulation; D005740:Gases; D008962:Models, Theoretical; D053758:Nanoparticles; D009716:Numerical Analysis, Computer-Assisted; D010316:Particle Size; D011312:Pressure; D013010:Sonication; D013016:Sound; D013696:Temperature; D014465:Ultrasonics; D014783:Viscosity; D014867:Water
chemical_list: D005740:Gases; D014867:Water