A Scaling Model for Droplet Characteristics in a Spray Cloud Arising From Wave Interactions With Marine Objects

Abstract

The objective of this study was to develop a model for predicting spray droplet size and velocity distributions during spray cloud formation arising from a wave impact with an object. The study looked at scaling issues and developed a scaling model to relate the spray characteristics measured in a tow tank to large-scale spray formations arising from wave impact with vessels. Several phenomena related to spray scaling have been studied to develop the scaling rules in large enclosures. These are wave theories for deep water, air entrainment process during the wave impact, water sheet disintegration and droplet size distribution as well as the scaling of two-phase flow interfaces (water/air). The focus of this study was on atomization and particle motions, and the thermodynamic part of scaling was ignored. The formation of upstream droplets caused by a wave impact on the bow of a vessel is the result of sheet and droplet breakup. Scaling models related to the process of air entrainment, which is caused by the wave impact, water sheet breakup, and spray cloud formation, were investigated to implement a comprehensive scaling model. A mathematical formulation, considering the aforementioned phenomena, was developed to calculate the final average droplet diameter and maximum run-up velocity. The effects of initial wave characteristics, the geometrical characteristics of the water sheet at the moment of water impact, and a spray parameter, on the final average droplet diameter were investigated. Predictions of wave characteristics and final droplet diameter are compared with previously published field observation data.