报 告 人：关剑辉 (James Guan) (University of North Carolina at Chapel Hill
报告时间：2025-1-17 10：00-11:00
报告地点：致源楼1206
主办单位：深圳大学物理与光电工程学院
报告人简介：
Dr Jian Hui (James) Guan received his Ph.D. in Physics from the University of Northumbria at Newcastle in 2017. He then worked as a post-doctoral research assistant in the Department of Engineering Science at the University of Oxford. Currently, he is a post-doctoral research associate in the Mathematics Department at UNC at Chapel Hill, where he doubles as an Assistant Teaching Professor in Mathematics. His expertise lies in experimental fluid mechanics, soft matter physics, and plant sciences. His research is published in Science Advances, Physical Review Letters, Langmuir, Soft Matter, Physical Review Applied, Physical Review Fluids, Scientific Reports, Journal of the Royal Society Interface, and most recently, in Nature Communications. His research has been recognized by awards such as the two APS' DFD Gallery of Fluid Motion award (including one Milton Van Dyke award) and has featured in National Geographic and the cover of Sciences Advances.
报告摘要:
In part one of this three-part talk, I will talk about the world's largest floating leaves - the giant Amazonian waterlily (genus Victoria). We studied how the structural form of the vasculature system underpins gigantism in these extraordinary leaves and inferred how this unique form of leaf gigantism evolved. Specifically, by means of mechanical testing and geometrical modelling, we found that the bending resistance of the Amazonian waterlily is considerably higher than of an elastic floating sheet of the same amount of material. In the second part, I will present a spontaneous symmetry-breaking instability that transforms standing Faraday waves into rapidly traveling waves, rotating either clockwise or anti-clockwise, in annular geometries. Combining experiments and simulations, we show that this traveling instability is driven and significantly enhanced by capillary effects, including wettability and contact-line dynamics. In the last part, I will demonstrate that vertically vibrated bubbles near a wall may undergo a spontaneous symmetry breaking in their harmonic shape oscillations, leading to steady propulsive motion. We characterize the dynamics of these self-propelled, or `galloping', bubbles in terms of the key system parameters, including bubble volume, driving frequency, and acceleration. Our results reveal that the bubble propulsion is intimately related to their resonant shape oscillations, which can be fine-tuned to produce a myriad of dynamics including rectilinear, orbital, and run-and-tumble motions.
