Numerical study of orientation effects on hydrodynamics and loading in an array of structures under solitary wave impact

Abstract

This study explores the impact of structure orientation on solitary wave-induced local hydrodynamics and loading in an array of structures, combining laboratory experiments and high-fidelity numerical simulations. Due to the complexity of the hydrodynamic processes involved, a comparative analysis of Reynolds-Averaged Navier–Stokes (RANS) k-ω SST and Large Eddy Simulation (LES) turbulence models’ performance was conducted using flume experiment data to identify the most suitable model. The LES model was chosen due to its superior capability to accurately capture high-frequency flow dynamics and resolve a broader spectrum of vortices. LES simulations were then performed on structure arrays arranged in two rows and three columns within a flat-bottom numerical flume. Structures were oriented at angles of 0°, 10°, 25°, 35°, and 45° clockwise relative to the incident wave direction, where orientation refers to the angle between the principal axis of an individual structure, centered around its cross-sectional centroid, and the direction of wave propagation. The results demonstrated significant effects of orientation on local hydrodynamics, including wave run-up, flow channelization, and vortex patterns. Symmetric orientations (0° and 45°) generated more uniform flow patterns, while asymmetric orientations (e.g., 25°) induced complex, irregular hydrodynamics. The 45° orientation yielded the highest normalized surface velocity due to greater flow blockage. Vortex dynamics varied significantly with orientation, with certain configurations enhancing mixing and energy dissipation within the structure arrays. The pressure and force analysis revealed distinct shielding effects of front-row structures for those in the back row across orientations. Seaside walls experienced the highest forces, while sidewall forces increased with orientation angle as they became more exposed to the wave. Conversely, forces on the opposing sidewall decreased with greater angles as they became more sheltered. The maximum net force increases with orientation, reaching 49 % higher in the front row and 18 % in the back row at 45° angle. Back-row structures consistently experience greater net forces primarily due to leeside pressure reduction from channelized flow and resulting wake vortices. This study underscores the critical role of structure orientation in coastal design and highlights the potential for optimizing array configurations to withstand diverse wave loading scenarios.