Effect of Interface Dynamics on Drag Reduction and Sustainability of Superhydrophobic and Liquid-Infused Surfaces in Turbulent Flow

Using Direct Numerical Simulation (DNS), with an entropic implementation of the free-energy lattice Boltzmann methods (ELBM) for multiphase flows [A. Mazloomi M, S. S. Chikatamarla and I. V. Karlin, Phys. Rev. Lett. 114, 174502 (2015)], we investigate the dynamics of the interfaces on SuperHydrophobic (SH) and Liquid-Infused (LI) surfaces in turbulent flow. ELBM allows for implicit interface capturing and adjustment of surface adhesion. As such, it can be used to investigate the depinning of the contact line and wetting phenomena. The DNS studies were performed in SH or LI turbulent channel flows at a bulk Reynolds number of Re_b=3600, corresponding to a base flow friction Reynolds number of Re_τ0≈222, for the range of Weber numbers 10^-3≤We_τ0 ≤10^-2 and viscosity ratios of 10 ≤ μ_ext/μ_int ≤60. Blade and scalloped longitudinal microgrooves with groove widths of 15≤ g⁺⁰≤ 63, in base flow wall units, and solid fractions of 1/64≤ φ_s ≤ 1/16 were investigated. A maximum advancing contact angle of θ_{F, adv} = 120^o was imposed in the simulations. The effect of Weber number, microgroove size and microgroove shape on the magnitude of drag reduction and sustainability of SH and LI surfaces will be discussed.