Hydrodynamic Characteristics of NACA0012 Hydrofoil with Modified Leading-Edge Designs under Undulatory Motion

Abstract The hydrodynamic performance of aquatic species is greatly influenced by their head morphology, which governs flow separation, vortex dynamics, and drag reduction. This research explores the impact of head shape on the swimming performance of undulatory bodies, using comparative analyses of two modified leading edge shapes with NACA0012 as baseline hydrofoil. The leading-edge radius, a key geometric parameter, is used as a metric to develop modified hydrofoils. This two dimensional numerical study investigates hydrodynamic characteristics, specifically thrust and lateral force generation, of foils across a range of Strouhal numbers (St = 0.4 to 1) at a constant Reynolds number (Re = 1000), non-dimensional undulation amplitude (Amax = 0.1) and wavelength (λ* = 0.8). The instantaneous vorticity contours depict the vortex dynamics, highlighting the transition from drag to thrust generation at higher St. The analysis shows that the base foil performs better at lower Strouhal numbers (St), exhibiting lower drag despite having a negative mean thrust coefficient (CTm) at St = 0.4. However, with an increase in St, the CTm for the thin foil improves and slightly exceeds that of the base foil at St = 1.0. This suggests that the thin foil is more efficient in generating higher thrust at higher St values.