Full-scale SPH simulations of ship-wave impact generated sea spray

Abstract

Sea spray generated by ship-wave impact contributes to marine ice accretion onboard vessels. Limitations in field measurements and model experiments encourage the use of numerical simulation to understand the formation of such spray. In this paper, full-scale computational fluid dynamics (CFD) models of wave-generated sea spray are developed using a smooth particle hydrodynamics (SPH) method. A three-dimensional (3D) numerical wave tank equipped with a flap-type wave maker and a wave absorber is created to produce regular waves of various heights and steepness. A full-scale medium-size fishing vessel (MFV) is modeled to encounter incoming waves at head sea conditions at various forward speeds. Moving ship dynamics with three degree-of-freedom (3-DOF) in waves are resolved instead of mimicking a relative ship speed. The resultant spray water amount is measured using a numerical collection box and compared against field measurements and a theoretical model, where a reasonable agreement is found. The model is able to distinguish between green water and spray water. A multi-phase two-dimensional (2D) simulation is also performed that demonstrates the role of winds in the fragmentation of water sheets into droplets. The simulation results indicate energy released from a surging ship significantly contributes to the generation of spray.