MASTER THESIS Analytical study of the interaction of water waves and submerged horizontal cylinders Francesco Fedele Dept. of Ocean Engineering , University Mediterranea , Reggio Calabria ITALY The diffraction of a periodic wave by a submerged horizontal cylinder is a genuinely problem of fluid mechanics with important consequences for offshore engineering. The mathematical problem has been studied firstly by Dean in 1948 and after by Ursell (1950)      and Ogilvie (1963). In 1995 and 1996 Boccotti gave a clear physical explanation of the interaction water waves and cylinders based on small-scale experiments.  In an article on the Proceedings of the Cambrige Philosophical Society, Dean proposed an      approximate method for the derivation of the analytical solution. Successively Ursell on the Proceedings of the Cambrige Philosophical Society, derived a semi-closed analytical solution of the diffracted velocity potential. The solution proposed by Ursell is lengthy and not easy to handle computationally. In 1963 Ogilvie in an article on Journal of Fluid Mechanics     proposed an expression of the velocity potential simpler than Ursell’s expression.  Recently Boccotti in two articles on the journal Ocean Engineering (1995 and 1996) has showed experimentally for the first time that the horizontal  force on a submerged solid body is greater than the horizontal force on an equivalent water volume of the solid body, because of a retardation of the  wave pressure fluctuations. Moreover the vertical force on a submerged solid body is greater than the vertical force on an equivalent water volume, because the magnitude of the pressure fluctuations increases on the upper part of the body and it decreases on the lower part of the body. In the thesis based on the Ogilvie’s solution the analytical predictions are compared to the experimental data of Boccotti and good agreement has been found. In particular it has been done -    A review of the simplified formulation of Ogilvie by analyzing the steps necessary to pass from the lengthy form of Ursell to the simplified form of Ogilvie, more useful for the applications; -    An analysis of the expression of the velocity potential of Ogilvie to predict analytically the retardation of the wave pressure fluctuations discovered experimentally by Boccotti. ( It is emphasized that the solution of Ogilvie, although simpler than Ursell’s solution, is computationally demanding because it is expressed as a series of infinite coefficients, the latter satisfying an infinite system of linear equations); -    A convergence analysis of Ogilvie’s solution; -    Examples of offshore applications relative to submerged horizontal cylinders. INTRO CHAPTER 1 CHAPTER 2 CHAPTER 3 CHAPTER 4 APPENDIX REFERENCES