A validation study on mathematical models of speed and frequency dependence in seakeeping

An extensive theoretical validation exercise is presented into the speed an d frequency dependent solutions associated with surface piercing vessels tr avelling in waves. The basis of the study lies in the formulation of the Gr een's function satisfying the traditionally posed linearized boundary value problem of an oscillating ship with forward speed and the development/impl ementation of appropriate numerical schemes of study for solution. Two widely different mathematical models in formulation and numerical algor ithm, denoted as methods A and B, are discussed and employed to predict hyd rodynamic coefficients, wave loads and responses of a Series 60 form and an NPL monohull. Only a selection of results are shown, but great care was ta ken in the overall investigation to verify and validate intermediate steps within the separate calculation procedures as well as to compare final pred icted values. The extensive qualitative and quantitative agreement of comparable results from methods A and B provides a measure of confidence that the presented fi ndings are solutions to the posed seakeeping problem. The influence of spee d and frequency dependence within the context of this study are discussed a s well as a preliminary study into their influence in the occurrence of irr egular frequencies in the numerical schemes.