報告人：呂鵬宇
報告題目：終極穩定的水下超疏水狀態（Ultimate Stable Underwater Superhydrophobic State）
邀請人：胡海豹 教授
報告時間：11月21日上午10:30-11:30
報告地點：航海學院201會議室
報告簡介：Superhydrophobicity of underwater structured surfaces is crucial to their functionalities like drag reduction, where a large area fraction of liquid-gas interfaces in the pinnedCassie-Baxter stateis required. However, various factors, such as pressurization, air diffusion, and liquid flow, will cause the instability of liquid-gas interfaces, leading to either wetting transition to the fully wetted Wenzel state or protrusion of bubbles into the liquid, which significantly influences the underwater performance. In the current work, stability of liquid-gas interfaces is investigated and various wetting states are directly observed and measured by confocal microscopy. The metastable state dynamically evolves owing to the air diffusion, which is extensively quantified under different ambient pressure conditions. A similarity law along with a characteristic time scale is derived which governs the lifetime of the air pockets. Air exchange between air pockets and surrounding water is therefore proved to be significant to the stability of liquid-gas interfaces. We then theoretically demonstrate and experimentally achieve an ultimate stable state on underwater superhydrophobic surfaces with arbitrary rough structures through the synergy of mechanical balance and chemical diffusion equilibrium across the interfaces. The equilibrium morphology of the meniscus can be tuned by adjusting the dissolved gas saturation degree under a given liquid pressure. The current results provide a further understanding of long-term stability of underwater superhydrophobicityand also promote their functionalities in practical applications.
報告人簡介：呂鵬宇，男，2015年在北京大學工學院力學與工程科學系獲得固體力學博士學位，2015年至2017年在荷蘭屯特大學流體物理課題組進行博士后研究?，F任北京大學工學院、北京大學工程科學與新興技術高精尖創新中心助理研究員。主要從事流固耦合界面力學的研究，包括微結構表面浸潤狀態與浸潤轉變、氣泡形貌演化、流體界面滑移特性、液滴蒸發溶解行為等研究方向，在《Physical Review Letters》、《Physics of Fluids》、《力學進展》等國內外主流期刊上發表SCI論文18篇（ESI高被引論文1篇），他人SCI引用140多次，國際專利1項，國家實用新型專利2項，2015年獲得北京大學優秀博士學位論文榮譽。
