液滴平壁铺展过程中的滞后效应及力学机制研究

发布时间：2018-06-01 14:19

本文选题：平壁铺展 + 接触角滞后　；参考：《应用数学和力学》2016年01期

【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.
[Abstract]:The lag effect of contact angle in the process of liquid droplet spreading is studied. The cause and variation of lag effect are considered from the point of view of the pressure, velocity and energy distribution of fluid near the contact line. On this basis, the influence of solid surface roughness on hysteresis effect is analyzed, and the quantitative relationship between solid surface morphology and contact angle hysteresis effect is established with the help of some 3D topography parameters (ISO 25178). In order to study the above content, the dynamic model of droplet spreading was established by using numerical simulation software, and the correlation verification was carried out with the hysteresis experiment on the solid surface. The results show that due to the existence of surface roughness, the liquid molecules located at the spreading front are pinned into the pits or valleys of the solid surface when the droplets spread to the equilibrium position, which makes the contact angle of the front gradually increase. The Laplace pressure driving droplet spreading and the balance between its own gravity and viscous resistance are the main mechanical mechanisms of the lag of contact angle. In addition, the experimental results show that the contact angle hysteresis effect is closely related to the surface morphology of the solid surface, and the solid surface with the same surface roughness (Sa) may have obvious differences due to the different contact angle hysteresis effects of the surface morphology.
【作者单位】：合肥工业大学摩擦学研究所;
【基金】：国家自然科学基金(51375132)~~
【分类号】：O35

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