Two-dimensional SPH simulations of wedge water entries

Review of water entry with applications to aerospace structures

Level set immersed boundary method for coupled simulation of air/water interaction with complex floating structures

A Smoothed Particle Hydrodynamics model for 3D solid body transport in free surface flows

In this work, we experimentally characterize the water entry of an asymmetric wedge into a quiescent fluid through particle image velocimetry (PIV). The wedge enters the water surface with an orthogonal velocity falling from a fixed height. We systematically vary the heel angle to elucidate the effect of asymmetric impact on the flow physics and on the fluid-structure interaction. The pressure field in the fluid is reconstructed from PIV data by integrating the Poisson equation. We find that the impact configuration significantly influences both the velocity and the pressure field, ultimately, regulating the hydrodynamic loading on the wedge. Specifically, as the heel angle increases, the location of maximum velocity of the flow moves from the pile-up region to the keel. At the same time, the pressure field significantly decreases in the vicinity of the keel, reaching values smaller than the atmospheric pressure. The spatiotemporal evolution of the hydrodynamic loading is thus controlled by the heel angle, with larger heel angles resulting into more rapid and sustained impacts.

Experiments on the water entry of asymmetric wedges using particle image velocimetry

Theoretical simulations are compared with drop test experiments of vessel free-fall impact on calm water, with zero and nonzero initial heel angles. The impact force and moment are predicted by using a theory described in Xu et al. (1998). The resulting motions of vessels at asymmetric impact include vertical water entry and transverse rolling. The downward deceleration equation combines the hydrostatic and hydrodynamic forces and the weight of hull, while the rolling equation takes into account the restoring moments due to asymmetry. Another simplified approach of a water entry dynamics and injury model (Gollwitzer and Peterson, 1996) is also applied to evaluate the impact acceleration for symmetric cases. The experiments were conducted at the Coastal Systems Station, Panama City, Florida, using a 2 ft × 8 ft (0.61 m × 2.44 m) prismatic hull model with 20 deg deadrise. The comparisons between the asymmetric impact theory and experiment shows varying degrees of qualitative and quantitative agreement.

Ronald Peterson

Papers

Asymmetric hydrodynamic impact and dynamic response of vessels

Asymmetric Hydrodynamic Impact and Dynamic Response of Vessels