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Numerical Simulation of the Water Exiting Process of Structure

Author: ZouXing
Tutor: LiHaiTao; ZongZhi
School: Dalian University of Technology
Course: Design and manufacture of ships and marine structures
Keywords: Water Exit Numerical Simulation Fluent Surface Deformation
CLC: U661.1
Type: Master's thesis
Year: 2013
Downloads: 53
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Abstract

As water exiting process of structure is used in ship and under water ordnance more and more widely, many countries put the great power on the basic research. And the research in this paper, to do a numerical simulation of the water exiting process of structure, is carried out under the background. The structure water exit problem is a complex problem, which is to be referred to water and air two-phase flow, also is coupled to the fluid flow field and rigid body kinematics. With the fluid mechanics analysis software Fluent, after knowing well about the key technology of dynamic mesh and UDF(User Defined Function), the research of a cylinder traveling normal to a plane interface with a constant speed is conducted, to get the data of flow field distribution and the interface deformation and the reaction on the body from the fluid.The research status of structure water exit problem at home and abroad is introduced. Most is the theoretical study on the water exit problem of simple models such as sphere and cylinder, and the experimental study with Particle Image Velocimetry (PIV), to get the distribution of velocity and vorticity and the change of deformation of free surface during the whole process of water exiting.As the flat plate flow and structure water exit problem both belong to high Reynolds number problems, the simulation of flat plate flow is done. The key information of which turbulence model be suitable for the problem of flowing around a body, with the boundary conductions and near-wall treatment, is known from the simulation, all of which will be an important part in the researching of water exit problem.Basing on the VOF model, simulation of a body water exit is completed. The distribution of velocity vector and vorticity around the axis-symmetric body are showed, also the curves of pressure on the four sides of the body, from which the dangerous point of each side can be seen, this can supply proof on the structural analysis and protect of missiles. Then the results of simulation and the experimental in literature were compared, they are in good agreement and this show the accuracy and reliability of simulation in researching the water exit problem.The quantitative analysis of the deformation of interface during the process of the structure traveling normal to the surface is made. The influence of the initial depth and the tips’shape on the interface deformation has been studied. Simulation of two body water exit is given out, also the differences of deformation when the bodies’distance and tips’shape change. Numerical simulation of three-dimensional structure water exit problem is conducted. And the interface shapes in different time are showed, from which the whole process of cylinder water exit can be seen clearly and intuitively. The splash on the body’s top and water fall off the tail and water upwelling in the free surface are saw apparently.

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