engleski

Development of Numerical Model for Green Water Loading by Coupling the Mesh Based Flow Models with the Meshless Models

The interaction between a moving vessel and incident waves leads to large relative motions and strong nonlinearities. This can result in violent water dynamics so that water flows onto the deck of the vessel, known as green water, and reaches crucial equipment and other deck structures. Green water events are considered as serious threat to the stability and operability of vessels, which should be reliably predicted and properly assessed in the design stage. Due to complexity of the problem, classification rules are limited in predicting the loads during the green water event. This thesis describes a novel method that is developed for simulating incompressible flows for the purpose of predicting green water events. The method is: meshless, Lagrangian, volume–conservative, second–order accurate, efficient, and suitable for coupling. The foundation of the method is a set of novel spatial operators based on the weighted–least squares, which are used to describe and solve the Navier–Stokes equations in strong form. Volume–conservative Lagrangian advection is used, which naturally handles violent free–surface flows. Boundary conditions are conforming to moving geometry at each time step. This makes coupling with other mesh–based and structural solvers straightforward. A completely parallel and efficient implementation of the methodology is described, which is verified by simulating cavity–flow, slamming, dam–breaking and sloshing experiments. The methodology is validated by simulating both isolated and periodic green water events simulated in a domain–decomposed environment. The computed kinematics and dynamics of the flows compare well with experimental data and results obtained by other numerical methods.

green water ; marine hydrodynamics ; free surface flows ; meshless method ; Lagrangian method ; finite differences ; domain decomposition

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