Quayson-Sackey, Emmanuel2025-07-302025-07-302025-07-29https://hdl.handle.net/10222/85254This study investigates the effect of surface slip on unsteady vortex dynamics around a NACA 64-618 airfoil at a Reynolds number of 1.3 × 10⁶ and angle of attack of 12°. A Navier-slip boundary condition, mimicking a superhydrophobic coating, was applied to evaluate its influence on turbulent flow behavior. Four slip lengths (Ls = 100 µm, 140 µm, 185 µm, and 400 µm) and a baseline no-slip case were analyzed. Instantaneous and mean velocity fields, frequency spectra, and proper orthogonal decomposition (POD) were used to characterize the flow. Slip was found to suppress trailing-edge separation bubbles and enhance wake flow acceleration. Shear-layer instability intensified, leading to early vortex roll-up. Frequency analysis showed a shift to lower dominant frequencies, especially for Ls = 400 µm, indicating small-scale vortex pairing. POD results revealed increased turbulent kinetic energy in the wake, concentrated within dominant mode pairs due to surface slip.enFrequency spectraNavier Slipnumerical simulationproper orthogonal decompositionturbulent flow