Wetting of doubly periodic rough surfaces in Wenzel’s regime

Stanimir Iliev,Pavel Iliev,Nina Pesheva,V.M Vassilev,S.G Nikolov,M.D Datcheva,Y.P Ivanova

doi:10.1051/matecconf/201814503006

Stanimir Iliev, Pavel Iliev + Show 5 more

Open Access

https://doi.org/10.1051/matecconf/201814503006

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Abstract

In this work we present preliminary results from our numerical study of the shapes of a liquid meniscus in contact with doubly sinusoidal rough surfaces in Wenzel’s wetting regime. Using the full capillary model we obtain the advancing and the receding equilibrium meniscus shapes for a broad interval of surface roughness factors. The contact angle hysteresis is obtained when the three-phase contact line is located on one row (block case) or several rows (kink case) of physical defects. We find that depending on the mutual disposition of the contact line and the lattice of periodic defects, different stick-slip behaviors of the contact line depinning mechanism appear, leading to different values of the contact angle hysteresis.

Highlights

For various industrial applications one needs to devise solid surfaces with prescribed wettability properties
Due to the presence of these defects, the liquid-vapor interface may move with the solid surface while the three-phase contact line (CL) is pinned at the surface defects and stays immobile relative to the solid surface
The difference of the advancing and the receding contact angle (CA) is called CA hysteresis (CAH), which is an important characteristic of the surface wettability

Summary

Introduction

For various industrial applications one needs to devise solid surfaces with prescribed wettability properties. Due to the presence of these defects, the liquid-vapor interface may move with the solid surface while the three-phase contact line (CL) is pinned at the surface defects and stays immobile relative to the solid surface This phenomenon can lead to the increase or decrease of the apparent contact angle (CA). For the wetting properties of such solid surfaces is characteristic the so-called stick-slip behavior of the CL and the existence of maximal and minimal apparent contact angles, called the advancing and the receding CAs adv and rec (ACA and RCA). These CAs are attained just before the CL unpins, resulting in a displacement of the whole liquid meniscus. We focus our study on the effect of the CL-depinning mechanism on the CAH in the case of smooth physical defects in Wenzel’s wetting regime

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