Numerical Simulation Of Fluid-Structure Interaction Arising From Bottom Slamming

As ships sail in rough sea, heave and pitch motions of ships are strong, which induce slamming loads on hull structures. Slamming loads can possibly cause local structure damage and whole hulls vibration or even break. Accidents of shipwreck often happen due to slamming loads. Thereby, it is practically necessary to investigate if the hull structure is able to sustain slamming loads at specific hull sections. There are three difficulties in the slamming field: unsteadiness of this course, great fluctuation of the liquid and nonlinearity of the interface between fluid and structure.In this thesis, fluid-structure interaction of the 2D rigid wedge entering into water is simulated using the finite element software ANSYS/LS-DYNA. In this numerical simulation, the wedge is represented by a Lagrangian grid with 4-nodes shell elements and the fluid is represented by an Eulerian formulation with 8-nodes brick elements. Penalty coupling algorithm in ALE is applied on the interaction surface which is identified as the fluid structure interaction interface. Consequently, the numerical results of the wedge's vertical acceleration are obtained with considering the structure's initial velocity, acceleration of gravity, boundary condition and so on. Comparisons between numerical result and experimental results show consistency.The thesis also synthetically investigates and analyzes various influence factors while the 2D wedge enters water. By using the same method, the slamming process of 2D rigid flat-bottom structure and flat structure of a trimaran's main hull keel are studied and some certain meaningful conclusion is gained. At the same time, unsloved problems and further research direction are pointed out.