Tohoku University · 재료과학
타쿠야 ヤマモト 교수의 연구실은 초음파 유도 현상, 특히 기계적 및 열적 상호작용에 기반한 다상유동 및 기포 역학을 중심으로 연구를 진행하고 있습니다. 주로 초음파에 의한 에멀스화 메커니즘, 기포의 비선형 진동 및 상호작용, 그리고 용융 금속 내 초음파 유도 유동(음향 스트림링)에 대한 실험 및 수치 해석을 수행하며, 응용 분야로는 금속 가공, 에너지 저장 소재, 나노에멀션 제조 등이 포함됩니다. 특히 기포의 붕괴가 액체 분리 및 미세 droplet 형성에 미치는 영향을 고속 영상과 수치 모델링을 통해 규명하고 있습니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
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
