Experimental and numerical analysis on the fluid flow behavior of a rigid trimaran model during water entry

This paper investigates the hydrodynamic characteristics of the vertical water entry of a truncated trimaran by combining experimental and numerical methods. A three-dimensional model was constructed using a scaled-down section of the stern. The water impact flow process within the range of drop heights from 200 to 800 mm was captured via a high-speed camera. The experimental test conditions were reproduced via the volume of fluid (VOF) method, and the load characteristics were supplemented. With pressure-converged mesh refinement, the numerical method aligns well with the experimental observations of bubble formation and deformation processes, although nonphysical merging phenomena occur during the bubble fragmentation stage. Within the range of impact velocities studied, on the basis of the established dimensionless system, similarities were found between the focused bubble volumes and shapes and those of a simple wedge-shaped body entering the water. In combination with the numerical results, key bubble characteristics, such as bubble shape, pressure and velocity fields, and bubble volume, were analyzed. With respect to the slamming load characteristics of practical applications, the influence of bubbles on the hull surface pressure was discussed, and the lack of correlation between the dimensionless pressure and impact velocity was revealed. These findings provide a theoretical basis for scaling flow and load transitions from models involving complex bubbles to full-scale models.