This article outlines fluid mechanics education in the Department of Mechanical Engineering in the Faculty of Science and Technology at Keio University, emphasizing actions towards internationalization of its curriculum. The undergraduate courses cover the full scope of F.M. White’s Fluid Mechanics as a required “English” textbook. One of the undergraduate lectures has been offered in English since 2022, attracting both exchange students and Japanese students and fostering cross-cultural interaction between them. On the other hand, the graduate courses address more specialized topics including turbulent flows, compressible flows, multiphase flows, and bio-inspired fluid dynamics. To align with international standards in undergraduate and graduate curricula, some advanced topics in fluid mechanics are to shift to graduate-level teaching in the coming academic year. These initiatives are expected to contribute to the creation of an international learning environment, which is essential for cultivating global leaders for the future.

An example of lectures on multiphase flow and related topics is briefly introduced. The curriculum concept for undergraduate and graduate students is also illustrated in the case of a department related to mechanical and aerospace engineering.

In industry, many processes handle various powder materials, and it is considered necessary to educate engineers to design equipment, manage, and evaluate based on an understanding of particle and powder characteristics. This article introduces an example of education on particle and powder characteristics, forces acting on particles, powder bed dynamics, powder flow, and unit operations such as fluidization and pneumatic conveying, focusing on the flow phenomena of gas-solid two-phase flows.

In this article, the background and overview of Topics in Multiphase Flow Engineering, corresponding to a course for graduate students in Graduate School of Engineering Science, Osaka University, are explained.

In the second semester of 1997, the Department of Mechanical Engineering at the Graduate School of Engineering at Osaka University began offering a course entitled “Fluid-Solid Multiphase Flow”. The course aimed to provide students with the fundamental knowledge and concepts necessary for conducting research on fluid-solid multiphase flows and their numerical analysis at the graduate level. At that time, various models and numerical methods in this field were developing rapidly, especially discrete particle models. This article describes the course's historical background and its contents.

The multiphase flow education in the University of Shiga Prefecture (USP) is presented. This lecture is for the master course students in the Department of Mechanical Systems Engineering, School of Engineering, USP given by the author. Syllabus of the lecture is referred precisely. The main topics covered in the lecture are the definition of multiphase flow, where we encounter the flow, the variation of the flow, flow regime and its map, the definition of parameters describing the flow, how to estimate volume fractions, pressure drops, and so on. Bubble engineering, especially for fine bubbles is also lectured. The author deeply desires the students of the lecture the extensiveness and the significance of the multiphase flow among many existence flows.

The lecture on multiphase flows needs teachers’ experience of research because of diversity of topics related to mathematical modeling, experimental discovery and flow assurances. The author emphasizes in each lecture with on-time solution of given problems even if its fluid dynamics is not perfectly established. This article picks up his way to teach two-phase flow circuits, multiphase rheology, volume-averaged conservation equations and motion equation of dispersions.

Based on his 18 years of teaching experience in the Department of Mechanical Engineering at Osaka University, the author offers his unique perspective on how fluid mechanics should be taught. Certainly, the solution methods and properties of solutions to individual partial differential equations, such as the Navier-Stokes equations, are important. However, the author's focus is more on the structure of fluid mechanics and the role that conservation laws play in education of fluid mechanics, including multiphase flows.

Ozone gel, which has strong oxidizing and disinfecting power, has attracted attention as a disinfection medium and a medical application for skin diseases. In this study, we attempted to develop a new fabrication method by blowing microbubbles directly into high-viscosity glycerin. Ozone gel is generally produced by dissolving high-concentration ozone gas in glycerin under high pressure, however the time-consuming and costly process using large-scale equipment prevents efficient production. In this study, we developed a novel ozone gel fabrication method by just blowing ozone microbubbles in highly viscous glycerin using a microbubble generation technique that uses powerful ultrasonic oscillation. Furthermore, by observing bubble generation behavior using a high-speed camera, it was confirmed that many microbubbles of the same size as those in water were generated in glycerin. Dissolved ozone concentration measurements and oxidizing power tests using indigo-carmine also revealed that the samples stably maintained a dissolved ozone concentration and oxidizing power sufficient for disinfection.

In this study, we measured pressure gradient dP/dz and void fraction α_G in spherical particle beds with particle diameters of 4 and 8 mm under stagnant liquid conditions. We obtained an empirical correlation and its uncertainty for the void fraction by using the data reported by Tutu et al. (1984), Chikhi et al. (2016) and ours. The uncertainty of the obtained α_G correlation was relatively small and ±2s = ±0.049 (where s is the standard deviation). However, the uncertainty band for the computed dP/dz was relatively large due to the uncertainty in the void fraction, ±2s = ±0.049. Effects of the interfacial friction F_i on computation of dP/dz were also discussed.

When wiping and cleaning with micro cloths containing ultrafine bubble water, there have been several comments that the sensation of resistance during wiping is reduced. In this study, we quantitatively investigated the resistance during wiping by measuring the frictional force between the micro cloth and the floor surface when the micro cloth was moistened with ultrafine bubble water. In the experiment, static and dynamic frictional forces were measured for four different base materials when the micro cloths were pulled at a constant velocity with a loaded mass on the micro cloths containing tap water and ultrafine bubble water. As a result, although the frictional resistance reduction effect was confirmed for the SUS plate, the clear effect could not be confirmed for the melamine board. In addition, the friction reduction effect was greater for smaller roughness of the base metal surface, and the presence or absence of the effect differed depending on the tensile speed of the cloth and the loaded mass of the cloth. In this experimental range, the frictional drag reduction effect was obtained in the case of the mirror-finished SUS plate under the most conditions.