Application of IITM-RANS3D to free-fall water entry of prismatic and non-prismatic finite wedges

High-speed watercraft and ships undergo coupled motions which make the front portion of the hull exit and violently re-enter water. This induces short-term slamming loads that may compromise the structural integrity of the hull. The slamming of the bow can be modeled as straight wedges of different deadrise angles (DRAs) falling into water from different heights. The advent of computational fluid dynamics has allowed the problem of wedge-slamming to be simulated using the full Navier-Stokes equations thus complementing the pioneering studies based on experiments. Recently, most researchers are opting to use commercial software to simulate the wedge-impact problem as it allows access to overset meshing algorithms which are robust in modeling the wedge as a moving body. Embedded boundary methods (EBMs) offer some advantages over overset meshing in that the mesh only needs to be generated once and Cartesian mesh-based solvers can be implemented. However, the application of EBMs to wedge-impact has been limited in the literature and merits further development. In this context, we investigate the applicability of the fast-fictitious-domain (FFD) based embedded boundary treatment to simulate the violent water-entry of wedges. We extend our in-house Navier-Stokes model IITM-RANS3D to handle floating bodies through integration of a rigid-body dynamics solver and an algorithm to embed three-dimensional stereolithography (STL) geometries as solids over a Cartesian mesh. The proposed algorithm is extensively benchmarked against variable DRA wedge-slamming experiments reported in the literature as well as constant DRA wedge-slamming experiments performed in-house. Very good agreement is reported in terms of the time-history of hydrodynamic impact pressures measured at various locations on the hull as well as the wedge motion responses thus demonstrating the suitability of FFD for simulating the coupled hydrodynamics of slamming for simplified hull geometries.