Tohoku University · Materials Science
Professor Takuya Yamamoto's research lab specializes in multiphase flows, ultrasonic phenomena, and advanced materials for energy applications. The lab investigates ultrasonic emulsification mechanisms, acoustic cavitation dynamics, and acoustic streaming in both liquids and molten metals, using high-speed imaging and numerical simulations. It also explores hydrogen storage properties in uranium-based alloys for potential applications in tritium storage and nuclear energy systems. The lab combines experimental techniques with computational modeling to understand complex interfacial and bubble dynamics.
Figures are computed from collected data and may differ slightly.
Summary Three numerical methods, namely, volume of fluid (VOF), simple coupled volume of fluid with level set (S‐CLSVOF), and S‐CLSVOF with the density‐scaled balanced continuum surface force (CSF) model, have been incorporated into OpenFOAM source code and were validated for their accuracy for three cases: (i) an isothermal static case, (ii) isothermal dynamic cases, and (iii) non‐isothermal dynamic cases with thermocapillary flow including dynamic interface deformation. Results have shown that
Aiming at elucidating ultrasonic emulsification mechanisms, the interaction between a single or multiple acoustic cavitation bubbles and gallium droplet interface was investigated using an high-speed imaging technique. To our best knowledge, the moment of emulsification and formation of fine droplets during ultrasound irradiation were observed for the first time. It was found that the detachment of fine gallium droplets occurs from the water-gallium interface during collapse of big cavitation bu
It is well known that ultrasonic cavitation causes a steady flow termed acoustic streaming. In the present study, the velocity of acoustic streaming in water and molten aluminum is measured. The method is based on the measurement of oscillation frequency of Karman vortices around a cylinder immersed into liquid. For the case of acoustic streaming in molten metal, such measurements were performed for the first time. Four types of experiments were conducted in the present study: (1) Particle Image
AbstractHydrogen absorption-desorption properties of some uranium-rich alloys were studied to develop an advanced material for temporary tritium storage. The characteristics of U-33.3at%Zr were analogous to those of U-69.7at%Zr, while the durability to powdering was reduced according to a decrease of zirconium content. The U-5.7at%Al exhibited a similar behavior to that of pure uranium including powdering to much extent, though a slight decrease in decomposition pressure was observed. The U-25at
Acoustic cavitation occurs in ultrasonic treatment causing various phenomena such as chemical synthesis, chemical decomposition, and emulsification. Nonlinear oscillations of cavitation bubbles are assumed to be responsible for these phenomena, and the neighboring bubbles may interact each other. In the present study, we numerically investigated the dynamic behavior of cavitation bubbles in multi-bubble systems. The results reveal that the oscillation amplitude of a cavitation bubble surrounded
Open papers in the app to read, cite, and organize with AI.
