Numerical analysis of energy dissipation and flow disturbance induced by underwater vehicle motion over rough coastal beds

This study numerically investigates the hydrodynamic behavior and energy dissipation generated by the motion of an underwater vehicle operating above rough coastal beds using a coupled Reynolds-Averaged Navier–Stokes (RANS) and Volume of Fluid (VOF) Computational Fluid Dynamics (CFDs) framework. Unlike prior studies that mainly addressed free-surface interactions or smooth seabed conditions, this work models realistic coastal roughness through sinusoidal seabed topography to analyze its influence on near-bed flow dynamics, vortex formation and wake turbulence. Simulations were performed across multiple vehicle velocities and roughness ratios to quantify variations in hydrodynamic forces, pressure fields and energy dissipation mechanisms. Results demonstrate that seabed roughness substantially amplifies turbulence intensity, broadens wake structures and increases drag and energy loss, driven by asymmetric pressure fields and intensified vortex shedding, especially in the near-bed region. The research fills a major gap in underwater vehicle CFD studies by establishing an integrated modeling framework that captures coupled vehicle–seabed–free-surface interactions, providing novel insights into the effects of seabed-induced turbulence on vehicle performance, energy efficiency and maneuverability in complex coastal environments.