Characterization of the Liquid–Lubricant Interface in a Dovetail Cavity for a Viscous Laminar Flow

Abstract

Lubricant-infused surfaces (LISs) have application in diverse fields based on their liquid-repellent properties. In bulk flow, LISs, however, are susceptible to drainage failure caused by external shear imposed at the liquid–lubricant interface. In this study, the shear-flow-induced lubricant depletion in a dovetail-shaped cavity microchannel has been numerically examined. Lubricant is exposed to five external liquids with different viscosities (μr = 0.2–1) in the laminar range (100 ≤ Re ≤ 1000). Temporal variations in the lubricant depletion from the microchannel and cavities were observed with time. Meniscus shapes were characterized for flows at different viscosity ratios. The results show that when the lubricant is kept fixed, a less viscous external liquid aids in better lubricant retention. Due to the shear imparted, three stable and two failure meniscus shapes have been distinguished. The results are further supported by vortex formation within the cavity and interface velocities contributing to meniscus shapes based on the magnitude of external shear. Additionally, it was evident that, as the viscosity ratio was reduced, the effect of the cavity opening was no longer dependent on the flow rate. It was envisaged that the results will help in the design of a robust LIS system.