北京大学力学与工程科学学院能源与资源工程系学术报告

报告人： Junichiro Shiomi

School of Engineering, The University of Tokyo

时间：2025年8月18日（周一）10:00-11:30

地点：北京大学新奥工学大楼2047

Dynamic wetting phenomena are present in many everyday situations where liquids interact with surfaces. Understanding and controlling the dynamics of droplets wetting solid surfaces is important in various applications such as boiling and condensation heat transfer, printing and coating, and microfluidic processes. However, modeling their dynamics is not easy because they are multiscale systems in which the advancing or receding of a nanoscale-thick contact line is linked to the behavior of the entire millimeter-scale droplet. In the Thermal Energy Engineering lab (TEEL) at the University of Tokyo, together with the collaborators, we have been investigating the droplet dynamics on solid surfaces as a model system, where the non-equilibrium nature of energy dissipation at the contact line becomes evident. On a partially wetting solid surface, when capillary forces drive droplet wetting, the advancement of the contact line is governed by viscous forces, inertial forces, or contact-line friction. Through experiments, we demonstrated that the dominant physical mechanisms can be switched by tuning droplet properties, surface microstructure, or applied electric field. We modeled and reproduced these experiments using a phenomenological parameter that quantifies the contact-line friction coefficient and mapped a phase diagram of dominant physical factors in a dimensionless parameter space. With the knowledge, we realized anisotropic wetting and droplet transport by taking advantage of the fact that the dynamic behavior of droplets can be controlled through solid surfaces when contact line friction is dominant. Furthermore, in our recent experiments on droplet oscillation and droplet sliding on solid surfaces functionalized with various self-assembled monolayers (SAMs), we observed that nanoscale surface chemistry and morphology significantly influence contact-line dynamics. This suggests that contact-line friction originates from nanoscale energy dissipation, though the dissipation mechanism remains unclear, and thus, it calls for collaboration with experts with multiscale discipline. 

Bio: Dr. Junichiro Shiomi is Professor in Institute of Engineering Innovation and Department of Mechanical Engineering, School of Engineering, the University of Tokyo. He is also currently Assistant Dean of School of Engineering, the University of Tokyo. He received B.E. (1999) from Tohoku University, and Ph. D. (2004) from Royal Institute of Technology (KTH), Sweden. Leading the Thermal Energy Engineering Lab, he has been pursuing research to advance thermal management, waste heat recovery, and energy harvesting technologies based on nano-to-macro innovation and materials informatics of materials, structures, and systems. He is fellow of Japan Society of Mechanical Engineers and members of Science Council of Japan and Engineering Academy of Japan. He serves as an associate editor of Nanoscale and Microscale Thermophysical Engineering. He is a recipient of the Zeldovich Medal from the Committee on Space Research, the Commendation for Science and Technology by the Minister of Educational, Culture, Sports, Science and Technology, the Academic award of Heat Transfer Society of Japan, the Academic Award of Thermoelectric Society of Japan, the JSPS Prize, and the Nukiyama Memorial Award.

联系人：杨荣贵 ronggui.yang@pku.edu.cn