NONLINEAR DIFFRACTION OF WATER WAVES BY OFFSHORE STRUCTURES

BSTRAT. This paper is concerned with a variational formulation of a non-axisymmetric water wave problem. The full set of equations of motion for the problem in cylindrical polar coordinates is derived. This is followed by a review of the current knowledge on analytical theories and numerical treatments of nonlinear diffraction of water waves by offshore cylindrical structures. A brief discussion is made on water waves incident on a circular harbor with a narrow gap. Special emphasis is given to the resonance phenomenon associated with this problem. A new theoretical analysis is also presented to estimate the wave forces on large conical structures. Second-order (nonlinear) effects are included in the calculation of the wave forces on the conical structures. A list of important references is also given. KEY WORDS AND PHRASES. Variational principle for non-axisymmetrlc water waves, non-linear diffraction of water waves, incident and reflected waves, wave forces, waves incident on harbors, and Helmholtz resonance. 1980 AMS SUBJECT CLASSIFICATION CODE. 76B15. I. I’DCTIOH. Diffraction of water waves by offshore structures or by natura