针对波纹状基底上含不溶性活性剂液滴的铺展过程,采用润滑理论建立了液膜厚度和浓度演化模型,通过PDECOL程序数值求解了演化方程组,得到了液滴的铺展特性及基底结构参数的影响规律。研究表明:当液滴铺展进入中后期,Marangoni效应减弱,此时基底的作用范围相应增大,基底对液滴铺展过程的影响逐渐显著。与平整基底相比,波纹状基底上的最小液膜厚度明显降低,而铺展前沿处的子波数显著增多,子波波峰高度呈单驼峰形的模态变化;而且,增加波纹状基底的高度或减小波数具有加剧液滴铺展不稳定性的作用。
For the spreading of an insoluble surfactant-laden droplet over corrugated topography,the lubrication theory is used to derive the evolution equations of liquid film thickness and interfacial surfactant concentration.The droplet spreading characteristics and the influence of topography structure are numerically simulated with PDECOL code.The results show that Marangoni effect is weakened and the effect of topography feature is enlarged obviously during the mid-late period of droplet spreading,which has a significant effect on the droplet spreading.Compared with spreading on flat substrate,the minimum film thickness over corrugated topography reduces apparently,and at the advancing front of the droplet,the number of wavelet tends to increase notably and the height curve of wavelet crest presents a single hump shape.The increased height and decreased wave number of corrugated topography give rise to the instability of droplet spreading.