Slamming loads and interaction behaviors on variable-curvature twin wedges during synchronous water entry

This paper numerically investigates the synchronous water entry of two-dimensional, variable-curvature twin wedges, representative of marine engineering catamaran structures. It aims to extend conventional flat-wedge studies to water entry behavior of complex curved geometries. A Cartesian grid multiphase flow framework is employed, integrating the radial basis function ghost cell method and the gradient augmented level set method for accurate treatment of moving boundaries and violent free-surface deformations. A systematic parametric study is conducted, encompassing five local curvature configurations (C1–C5), five inter-body spacings (G0 = 0.2–2.0), and two water entry velocities (2.77 and 13.85 m/s). Results reveal that geometric curvature is a dominant parameter influencing pressure distribution. For wedges with higher curvature (i.e., blunter configurations), the peak slamming pressure increases significantly due to stronger fluid accumulation and reduced flow separation. In contrast, wedges with sharper profiles tend to promote earlier flow separation, leading to lower, pressure peaks. Moreover, the spacing between the twin hulls modulates the hydrodynamic interaction. At small spacing, the interference between the two wedges leads to pronounced pressure amplification and increased load fluctuations, whereas larger spacing tends to decouple the flow fields, making the water entry process resemble that of single-wedge cases. The present model also captures transient phenomena such as spray jets, splash formation, and free-surface fragmentation. These conclusions provide a basis for the design and optimization of curved twin bodies, such as high-speed ship bows/bottoms and seaplane floats.