Numerical Methods Research And Application On 2D Water Impact Problem Of Wedge Body

Water impact problem is a typical slamming problem in ship and marine engineering. In recent years, with the increasing of marine power and speed, the accidents of structural damage caused by the bottom of the ship bow slamming increased as well. So, there is great significance for an accurate assessment of slamming force to structure strength and performance. This paper focuses on the 2D water impact problem of wedge body with different numerical methods, and comparative analysis was showed in the same time.Firstly, this paper describes the slamming phenomenon where the ships and marine structures were encountered, and thus leads to a specific problem - water impact. Depending on the research work done before, this paper briefly classifies the different methods for solving this problem and analyzes the key issues.Secondly, the basic theory of the boundary element method and SHP method are studied.The first part discusses the potential flow theory based on boundary element method, and the solving process of ideal fluid using linear elements and discusse SPH method based on the Navier-Stokes equations and its basic theory. The second part describes the theoretical basis of Von Karman model, the Wagner model and the MLM model. Specifically, the comparing and the analysis were also showed in this paper.Thirdly this paper sets up a mathematical model based on potential flow theory to study the water impact problem. A numerical stimulation program based on boundary element method is used to accurately calculate the shape of the free surface when the jets are ignored.The result shows that this method is accurate and efficient when the deadrise angle is small.Fourthly this paper simulates the process of the water impact problem of wedge body by using SPH method based on N-S equations. The result is compared with the result based on boundary element method. SPH method is less accurate than boundary element method in calculating the pressure curve. But SPH method can stimulate the jets part of the water impact problem very well and simplifies the free-surface problem because of its mesh-free property.Finally , this paper uses the application of the finite element software ANSYS , the bow will be modeled and analyzed the strength of the bow. The resulting load will be compiled in ANSYS with APDL language to analyze the strength of the structure, and reasonable opinion in design of the bow was given as well.On the one hand, this paper verified in the case of deadrise angle ignoring the impact of jet by using the boundary element method, therefore, the accurate calculating of the slamming force could be acquired. On the other hand comparing the boundary element method and SPH method, analyzing their strengths and weaknesses, numerical methods can be easily selected to solve specific problems. While as an example of a bulk carrier segment,the conclusions can be used to the actual project.