Wave-impact spray on marine vessels and structures: Literature review

Sea-spray icing of ships and structures poses significant risks to vessel stability and crew safety. The biggest source of marine icing is wave-impact spray, i.e. spray resulting from a ship-wave collision. Numerical data on spray cloud generation, airborne phase and impingement on the surface are scarce and uncertain. Extensive but poorly documented research on sea spray icing was performed in the Soviet Union in the 1970 and 1980s, followed by North American and European studies. Later, computer technology was used to upgrade simple relation-based models to flexible code-based algorithms. Despite progress, the spray generation phase remains poorly understood, leading to uncertainties throughout the spray process. The external parameters of the spraying process include environmental (wind velocity and sea state) and vessel-related ones (vessel geometry, speed, heading and motions), and the intermediate factors include droplet properties and trajectories, spray concentration and collection efficiency. The complex interplay between the factors and processes involved in spraying is hard to model explicitly, and the direct correlations between spray flux and environmental parameters are limited and case-specific. Modern tools like computational fluid dynamics and machine learning hold promise for wave-impact spray research but require robust real-world data for validation. Future research should aim at developing a concise methodology of spray measurements, collecting more data, and employing advanced digital technology for spray modeling.