中文摘要：

研究了液滴平壁铺展过程中的接触角滞后效应,从接触线附近流体的压力、速度以及能量分布等角度考虑滞后效应的成因和变化规律.在此基础之上分析了固体表面粗糙度对滞后效应的影响,并借助部分三维形貌参数（ISO 25178）建立了固体表面形貌与接触角滞后效应之间的量化关系.为了研究以上内容,应用数值仿真软件建立了液滴铺展动力学模型,并结合固体表面上的滞后性实验进行了相关验证.研究结果表明：由于表面粗糙度的存在,液滴铺展至平衡位置时,位于铺展前沿的液体分子被钉扎在固体表面的凹坑或低谷中,使得前沿接触角逐渐增大,后沿接触角逐渐减小,接触角发生滞后;驱动液滴铺展的Laplace压力和自身重力与阻碍液滴铺展的黏性阻力之间的平衡关系,是接触角发生滞后的主要力学机制.另外,实验结果表明接触角滞后效应与固体表面形貌密切相关,具有相同表面粗糙度（Sa）的固体表面,由于表面形貌不同接触角滞后效应可能存在明显的差异.

英文摘要：

Contact angle hysteresis（CAH） is one of the significant phenomena in the process of droplet spreading on solid surfaces.It plays an important role in mechanical lubrication and other industrial applications.CAH on both smooth and rough surfaces was studied through parametric analysis based on numerical simulation and ISO 25178.The changes of kinetic energy of molecules,liquid pressure and flow velocity near the moving contact line（MCL） related to the mechanism of CAH were investigated with the Flow-3D software.In addition,quantitative tests of the relationship between surface roughness and CAH were conducted with several key parameters according to ISO 25178.The results show that the contact angle is not usually equal to the Young＇ s contact angle because of the influence of surface roughness;the dynamic balance between sliding force（caused by Laplace pressure and droplet gravity） and viscous resistance（caused by surface roughness） at the MCL is the main reason for the occurrence of CAH.Moreover,CAH is closely related to surface topography,the CAH results on various substrates with different micro-texture types show great differences.The present study enhances the understanding of the CAH mechanism from a micro-perspective and provides some guidance for the practical manufacture of surfaces with better lubrication property and wettability.