改性疏水固壁润湿性反转现象的格子Boltzmann方法模拟

基于疏水固壁改性会引起润湿性反转的特点,采用考虑固体与液体间分子力的格子Boltzmann方法,从壁面的线性和瞬时改性两方面对润湿性反转现象进行了数值模拟,并结合流体体积方法处理界面层质量.结果表明:壁面线性改性的过程中润湿性反转变化平稳,润湿所需时间大幅减少,所得到的接触角与固液吸引力系数的关系与其他文献结果一致;壁面瞬时改性幅度越大说明固壁对液滴作用力越强,表现为润湿性变化越明显,瞬时改性后接触角随时间呈指数规律变化,这与现有结论相符合.研究发现:在改性条件下液膜铺展过程中伴随着振荡变化,线性改性的振动峰值与改性幅度相关;瞬时改性的液膜速度会在某一时刻突然增大,这种现象与夹带空气有关.

Wettability alteration simulation of modified hydrophobic solid surface by lattice Boltzmann method

Based on the wettability alteration caused by the modified hydrophobic solid surface, the phenomenon of wettability alteration is simulated numerically in terms of linear and instantaneous modification by using the lattice Boltzmann method which can properly reflect the interaction of solid-liquid molecules, combined with the volume of fluid method to dispose the quality of interface layer. Results show that the wettability changes smoothly in the process of linear modification, the time needed for wetting significantly decreases, and the relationship between the contact angle and attractive coefficient of solid-liquid accord well with literature data. The more greatly the amplitude of instantaneous modification changes, the stronger the force of solid acting on droplet is, which is reflected by the obvious change of wettability. It is also found that the contact angle changes exponentially with time after instantaneous modification, which is in good agreement with the existing conclusions. Further investigation shows that the liquid oscillation exists in the whole spreading process. The vibration peak is associated with the modified amplitude of linear modification. And liquid film velocity increases suddenly at sometime after instantaneous modification, which is associated with entrained air.
Keywords： modified hydrophobic solid surface wettability alteration lattice Boltzmann method numerical simulation