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.