含表面活性剂液膜去湿过程的数值模拟

对存在壁面滑移的含非溶性表面活性剂薄液膜在固体表面的去湿过程,采用PDECOL程序对描述其演化过程的液膜厚度和表面活性剂浓度方程组进行数值求解.基于液膜表面扰动波形的变化,分析各参数对去湿特性及液膜稳定性的影响规律.研究指出:Marangoni数M较小时其效应使液膜失稳区缩短,而M较大时液膜失稳区间无限延伸,稳定性降低;毛细力数减小使液膜失稳区间缩短,减至一定程度后可有效抑制去湿现象的发生;滑移效应对演化过程的影响与M有关,M较小时滑移使液膜失稳区间缩减,使扰动增长率增大,M较大时这一影响并不显著;随平衡液膜厚度增大,液膜表面的扰动程度减小,但扰动区间显著增大.相对于外源性表面活性剂而言,内源性情形的失稳区间更小,液膜稳定性更强.

Numerical Simulation on Dewetting of Thin Film Containing Insoluble Surfactant

Dewetting of thin films covered by insoluble surfactant in the presence of wall slippage is considered.PDECOL program is used to simulate evolutions of film thickness and surfactant surface concentration.With perturbation wave variation of film surface,effects of several parameters on dewetting dynamics are examined.It shows that Marangoni stress shortens unstability region at small Marangoni number(M) and the unstability region is extended at large M.Decreasing capillary number leads to shorten unstability region and even restrains dewetting phenomena.The influence of slipping is closely related to M,and it accelerates perturbation growth and shorten dewetted region at small M.Increasing equilibrium film thickness leads surface deformation degree weakened and unstability region extended.Compared with exogenous surfactant,endogenous forms a shorter dewetted region and hence film stability tends improved.