液滴在非互溶大黏度比液体表面的铺展特性

Spreading of a Droplet on Surface of an Immiscible Liquid with High Viscosity Ratios

利用基于润滑理论的液滴在非互溶液体表面铺展的物理模型,探讨大黏度比情形下黏度比对液滴演化过程和平衡形状的影响,分析液滴厚度、铺展半径等特征参数的变化。结果表明:接触线附近液—液界面的变形受黏度比和表面张力比的影响;提高黏度比将导致铺展速率降低、时间常数减小,进而延长演化历程,但不影响液滴最终稳定形状;铺展半径与时间的关系满足x_(max)=1-0.2 exp(-βt);大黏度比液滴铺展后期并未出现小黏度比时的惯性振荡现象。

A mathematical model of droplet spreading on surface of an immiscible liquid based on lubrication approximation was used. Influence of viscosity ratio on evolution and equilibrium state of droplet at high viscosity ratios was investigated. Crucial parameters including droplet thickness and spreading radius were examined. It shows that deformation of the liquid-liquid interface near the contact line is affected by the viscosity ratio and the surface tension ratio;Increase of viscosity ratio reduces the spreading rate and the time constant, thereby, prolongs the spreading evolution. It does not affect the final stable shape of the droplet;Relation between spreading radius and time satisfies x;= 1-0.2 exp(-βt). Inertial oscillation does not appear at the final stage of droplet spreading in the case of high viscosity ratios.