Numerical Investigation on the Water Entry of Convex Objects Using a Multiphase Smoothed Particle Hydrodynamics Model

In this paper, the hydrodynamic behaviors of a typical convex object during water entry are numerically investigated using a meshfree particle method, smoothed particle hydrodynamics (SPH). In order to consider the practical air-cushion effects during water-entry process, a multiphase model with interface force is incorporated to the SPH method to maintain sharp water-air interface. Three numerical examples including bubble rising, water impact on a flate plate and water entry of a wedge are firstly simulated to validate the effectiveness of the multiphase SPH method in predicting the slamming forces and trajectories of falling objects. Water entry of free falling convex objects with different shapes and sizes is then simulated using the validated numerical method for comparative studies. Two slamming processes, including the convex slamming and the structure slamming, are observed in simulations, with double-jetting pattern occurring after the structure slamming. The air-cushion effects are well captured with slamming-induced vortexes clearly shown in the simulation snapshots. Quantitatively, significant drop in pressure peak value is observed when the dimensionless width of the convex is larger than 0.2. Among various shapes of convexes, the square shaped convex experiences the minimal local pressure peak value.