Green sea loads in irregular waves with Finite Volume method

Abstract Extreme green sea loads upon a vertical deck structure of an Ultra Large Container Ship are calculated in this paper using Finite Volume based CFD simulations in full scale, where two different approaches for the definition of the Equivalent Design Wave are used. Linear frequency–domain method is used to calculate the long–term response in terms of Relative Wave Elevation, which in turn is used to define a deterministic Equivalent Design Wave which is then used in the CFD simulation. The simulations are conducted using a newly developed flow model that takes into account air compression in violent free–surface phenomena. Regular Equivalent Design Wave and Response Conditioned Wave approaches are used and compared in terms of loads exerted on the deck structure and required computational resources. Some differences in loads are found between the methods, whilst similar computational resources are required. The Regular Equivalent Design Wave gives larger loads, making it a safer choice. However, the Response Conditioned Wave takes into account the relevant ocean wave conditions as well as the response of the ship, resulting in smaller loads which would enable smaller structural scantlings and cost savings.