Gazi Arman Hossain, Md Absar Jahan, Nayem Zaman Saimoon, Md. Mahmudul Hasan, Mahadi Hasan Masud
This study investigates the structural response of underwater glider (UWG) wings with various profiles for minimising vortex-induced vibrations (VIVs) and enhancing operational stability. Three wing geometries, a conventional rectangular cross-section (RCS), a NACA 2412 airfoil, and a biomimetic profile inspired by the Green Sea Turtle (GST), were compared through transient computational fluid dynamics (CFD) and modal analysis. Vortex shedding frequencies (VSFs) were determined by Fast Fourier Transform (FFT) of unsteady lift coefficients and compared to natural frequencies corrected for added mass in underwater conditions. The result shows that the GST-inspired wing offers superior stiffness and reduced unsteady loading, while the NACA 2412 and the RCS profiles achieved efficient flow attachment but may be more susceptible to resonance due to closer alignment of VSFs and modal frequencies. Results show that the GST-inspired wing exhibits the largest gap between hydrodynamic and structural frequencies, with around 132.33 Hz difference between its VIV and wet-modal frequencies, compared with 28.14 Hz for the RCS and 108.99 Hz for the NACA 2412. Thus, the GST wing demonstrated sufficient difference between hydrodynamic and structural timescales, minimising resonance risk. These findings demonstrate that the baseline NACA 2412 airfoil and biomimetic-based wing designs are promising for vibration attenuation and increased UWG endurance.