Potential Theory Of Large-scale Vertical Cylinder In Ocean Wave And Its Application

Vertical cylinder is an essential structure in offshore engineering.For construction or internal layout convenience,polygons are common type of trans-section of it.In the sizing phase,there may be thousands to millions of candidates need to be analyzed.To get accurate wave loads in limited time,a quick and precise method which is different from BEM is needed.Only a few simple geometry shapes can be solved analytically,such as vertical or horizontal round cylinders.BEM is widely used in offshore engineering as a reliable method,however,in the screening phase,a fast and accurate alternative way is necessary for massive candidates.“Wave-cylinder” interaction is a typical general model in physics,to look deep into its mathematical features helps to understand its physical mechanics.So,to study arbitrary section cylinder's wave loads analytically is the main aim of this dissertation.In this dissertation,following analytical way for vertical circular cylinder wave potential,with the help of conformal mapping technology,by using the series expansion of arbitrary trans-section onto exterior of unit circular,wave potential equation in the mapped plane is derived and the solutions are classified with the boundary conditions for diffraction problem.Verification test cases show good consistency with BEM results.By combining the mathematical method of arbitrary section bottom-mounted cylinder and truncated round-section vertical cylinder,the truncated arbitrary section vertical cylinder is also studied,and similar results as BEM are obtained too.The verification cases show the reliability and feasibility of the analytical method proposed in the dissertation.The model of scattering by a non-circular trans-section is a general basic mathematical problem,which is analyzed with the help of conformal mapping in this paper.The techniques to handle the governing equation and boundary conditions in the mapped plane provide reference for the similar problems in other disciplines such as truncated vertical cylinder in hydrodynamics,wave scattering by cylinder in Acoustic,Electromagnetics etc.