報(bào)告人：呂鵬宇
報(bào)告題目：終極穩(wěn)定的水下超疏水狀態(tài)（Ultimate Stable Underwater Superhydrophobic State）
邀請(qǐng)人：胡海豹 教授
報(bào)告時(shí)間：11月21日上午10:30-11:30
報(bào)告地點(diǎn)：航海學(xué)院201會(huì)議室
報(bào)告簡(jiǎn)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(bào)告人簡(jiǎn)介：呂鵬宇，男，2015年在北京大學(xué)工學(xué)院力學(xué)與工程科學(xué)系獲得固體力學(xué)博士學(xué)位，2015年至2017年在荷蘭屯特大學(xué)流體物理課題組進(jìn)行博士后研究。現(xiàn)任北京大學(xué)工學(xué)院、北京大學(xué)工程科學(xué)與新興技術(shù)高精尖創(chuàng)新中心助理研究員。主要從事流固耦合界面力學(xué)的研究，包括微結(jié)構(gòu)表面浸潤(rùn)狀態(tài)與浸潤(rùn)轉(zhuǎn)變、氣泡形貌演化、流體界面滑移特性、液滴蒸發(fā)溶解行為等研究方向，在《Physical Review Letters》、《Physics of Fluids》、《力學(xué)進(jìn)展》等國(guó)內(nèi)外主流期刊上發(fā)表SCI論文18篇（ESI高被引論文1篇），他人SCI引用140多次，國(guó)際專(zhuān)利1項(xiàng)，國(guó)家實(shí)用新型專(zhuān)利2項(xiàng)，2015年獲得北京大學(xué)優(yōu)秀博士學(xué)位論文榮譽(yù)。
