A comprehensive experimental and numerical study of Taylor–Couette flow on superhydrophobic surfaces

Superhydrophobic surfaces (SHSs) have garnered significant attention for their potential to reduce hydrodynamic drag under underwater flow conditions. This study investigates the effectiveness of SHSs in reducing drag within Taylor–Couette (TC) flow, a classical fluid dynamics system characterized by the flow between two concentric, rotating cylinders. By employing SHSs on the inner cylinder, we demonstrated a substantial decrease in drag with the implementation of SHSs, particularly in the turbulent regime. To illustrate underlying physics for altered flow behaviors on SHSs, we developed a numerical model based on Navier’s slip model to simulate the rotating SHSs. The simulations were conducted using both medium and high fidelity numerical methods, including unsteady Reynolds-averaged Navier–Stokes and large eddy simulation, which were validated against experimental results in terms of shear stress and velocity profiles. In addition, we employed particle image velocimetry to visualize flow patterns and phenomena in the TC apparatus. The quantitative analysis of flow patterns, vortex formation, and the Reynolds stress tensor was conducted for comparison between smooth surface and flat SHSs. The results showed that the slip velocity decreased the average velocity of the SHS rotor while increasing velocity fluctuations in the TC flow. The heightened velocity fluctuations are due to greater instability from the slip condition, leading to smaller but more numerous vortical structures near the wall. By experimental validation, our numerical model has been proven to understand the role of surface properties in fluid dynamics in the TC flow and may contribute to future advancements in relevant technologies.