Roughness on liquid-infused surfaces induced by capillary waves

Liquid-infused surfaces (LIS) are a promising technique for reducing friction, fouling and icing in both laminar turbulent flows. Previous work has demonstrated that these susceptible to shear-driven drainage. Here, we report different failure mode using direct numerical simulations of channel flow with liquid-infused longitudinal grooves. When the liquid-liquid surface tension is small and/or grooves wide, observe traveling-wave perturbations on interface amplitudes larger than viscous sublayer flow. These capillary waves induce roughness effect increases drag. The generation mechanism explained theory developed by Miles gravity waves. Energy transferred from LIS provided there negative curvature mean at critical layer. Given groove width, Weber number an estimate friction Reynolds number, provide relations determine whether behaves as smooth or rough