Abstract:

Self-propelled droplet jumping has widespread applications in surface cleaning, condensation heat transfer, hydrogen production, and triboelectric nanogenerator due to the passive yet effective cross-interface transfer of mass, momentum, energy and charges, whose rates generally increase with droplet size. However, as droplet size increases, gravity inevitably impedes droplet’s mobility, imposing a capillary length constraint of 2.7 mm for water droplet, beyond which self-propelled jumping remains a persistent challenge. Here, we report passive jumping of water puddle in the unprecedented centimeter scale from a superhydrophobic surface through the burst of an entrained bubble, breaking the capillary length limitation for droplet jumping. By virtue of direct and localized impact at droplet base, the bubble-burst-induced capillary waves play a paradigm-shifting role in shortening the impact duration, depressing droplet spreading, and facilitating momentum transfer. With >90% conversion to droplet jumping momentum, the impacting momentum of capillary waves scales linearly while droplet jumping height scales quadratically with bubble radius. Through studying the synergistic interplay between bubble bursting, fluidic jetting and droplet jumping, this work reveals a previously unexplored mechanism of capillary wave impact in fluid-structure interactions and offers a promising strategy for droplet actuations and the directional printing of particles in additive manufacturing.

Introduction of speaker:

Dr. Jiangtao Cheng received his Ph.D. degree in Physics from Purdue University in 2002. He also has a M.S. degree in Computer Science from Purdue University and a B.S. degree in Applied Physics from Peking University. Prior to joining the Department of Mechanical Engineering at Virginia Tech in 2015 as Associate Professor, Dr. Cheng was a research scientist at Teledyne Scientific Company (formerly Rockwell Science Center). He has extensive experience in micro/nano-fluidics, optofluidics, thermal-fluid sciences, multiphase fluid flow, micro/nano-fabrications and CFD numerical simulation. He has authored more than 90 papers in these fields. Dr. Cheng has been on the editorial boards of eight international journals. He has won 6 times of Best Paper/Best Poster Awards in various international conferences. In 2010, Dr. Cheng’s project “Optofluidic Solar Concentrators” was announced by the U.S. Department of Energy as one of the “six transformational energy research and development projects that could revolutionize how the country uses, stores, and produces energy”. In 2013, he received Outstanding Overseas Young Scholar Award from China NSF. Dr. Cheng became elected faculty fellow of College of Engineering at Virginia Tech in 2019 and was named a fellow of the American Society of Mechanical Engineers (ASME) in 2021. He won the New Directions award of American Chemical Society (ACS) Petroleum Research Foundation in 2026. His recent work on “Bubble-burst-induced puddle jumping and jet printing” was reported as editor’s choice by Physics World of Institute of Physics (IOP).

审核：刘有晟、游小清