The direct observation of cavitation bubbles emerging in liquid mercury under the action of mechanical impacts and theoretical investigations on the experimental results have been made. Through a glass wall, the image of cavitation bubbles appearing near or in contact with the wall was captured by high-speed cameras. Discrepancies found between the bubbles' growth rates determined experimentally and given by a single-bubble theory have been discussed using a theoretical model of Rayleigh-Plesset type that takes into account bubble-bubble and bubble-wall interactions. A theoretical equation for the asymptotic growth rate in a multibubble case has been given and time dependence of the growth rate under a constant negative pressure has been clarified.
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http://dx.doi.org/10.1103/PhysRevE.75.046304 | DOI Listing |
Ultrason Sonochem
December 2024
School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China; MOE Key Laboratory of Cryogenic Technology and Equipment, Xi'an Jiaotong University, Xi'an 710049, China.
Cavitation plays a crucial role in the reliability of components in refrigeration systems. The properties of refrigerants change significantly with temperature, thereby amplifying the impact of thermodynamic effects. This study, based on the Large Eddy Simulation (LES) method and the Schnerr-Sauer (S-S) cavitation model, investigates the transient cavitating flow characteristics of the R134a refrigerant in a Venturi tube (VT).
View Article and Find Full Text PDFUltrason Sonochem
December 2024
School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China; Tianjin Key Laboratory of Chemical process safety and equipment technology, Tianjin 300350, China. Electronic address:
Ultrasonic reactors, widely applied in process intensification, face limitations in their industrial application due to a lack of theoretical support for their structural design and optimization, particularly concerning the uniformity of the cavitation zone. Addressing this gap, our study introduces a novel approach to design a multi-frequency octagonal ultrasonic reactor of capacity 9.5 L through numerical simulation and spectrum analysis.
View Article and Find Full Text PDFUltrasonics
December 2024
Department of Physics, Concordia University, Montreal, Quebec H4B 1R6, Canada; Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada. Electronic address:
Clinical ultrasound contrast agent microbubbles remain intravascular and are between 1-8 µm in diameter, with a volume-weighted mean size of 2-3 µm. Despite their worldwide clinical utility as a diagnostic contrast agent, and their continued and ongoing success as a local therapeutic vector, the fundamental interplay between microbubbles - including bubble-bubble interaction and the effects of a neighboring viscoelastic vessel wall, remain poorly understood. In this work, we developed a finite element model to study the physics of the complex system of two different-sized bubbles (2 and 3 µm in diameter) confined within a viscoelastic vessel from a resonance response perspective (3-12 MHz).
View Article and Find Full Text PDFLasers Med Sci
December 2024
University of Zurich, Zurich, Switzerland.
Laser-activated irrigation (LAI) of root canal systems depends on the generation of cavitation bubbles in the endodontic irrigant. Physical studies thus far focused on pulse energy, pulse length, frequency, and fiber tip shape, mostly in plain water. This study investigated the effect of endodontically relevant molecules (sodium hypochlorite (NaOCl), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), and their combination) in water on physical properties of the resulting solution, and their impact on primary cavitation bubble features.
View Article and Find Full Text PDFUltrason Sonochem
December 2024
Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario, Canada; Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between St. Michael's Hospital and Toronto Metropolitan University, 209 Victoria St, Toronto, Ontario, Canada.
This study presents an experimental investigation of the influence of MB concentration on the resonance frequency of lipid-coated microbubbles (MBs). Expanding on theoretical models and numerical simulations from previous research, this work experimentally investigates the effect of MB size on the rate of resonance frequency increase with concentration, a phenomenon observed across MBs with two different lipid compositions: propylene glycol (PG) and propylene glycol and glycerol (PGG). Employing a custom-designed ultrasound attenuation measurement setup, we measured the frequency-dependent attenuation of MBs, isolating MBs based on size to generate distinct monodisperse sub-populations for analysis.
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