TIME DOMAIN PROGRAM OF SHIP MOTIONS AND SEA LOADS IN IRREGULAR HEAD SEAS. USER'S MANUAL

Authors
  1. Johnston, G.W.
  2. Foster, S.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN);Aerospace Engineering and Research Consultants Ltd, Downsview ONT (CAN)
Abstract
A Fortan algorithm has been developed for time-domain prediction of wave-body interactions, including hull motions and hyrodynamic loads, in three dimensions. The algorithm is divided into three main modules which separately address the problems of hydrostatic equilibrium, hydrodynamic impulse response characteristics and the longitudinal equiations of motion. Hydrostatic equilibrium is determined by solving the nonlinear 2 x 2 system of equations for the vertical position of the waterplane (with respect to the body centre of gravity) and trim. Hydrodynamic impulse response characteristics are determined by solving a boundary integral equation for body surface potentials using a collocation method. Each hydrodynamic impulse response is inferred from the potentials so computed given a prescribed non-impulsive motion input. With these impulse response functions, hull motions and sea loads are computed by solving the longitudinal equations of motion using an Adams-Bashforth 3-step time marching scheme. Nonlinearities introduced by a time-dependent hull geometry are optionally addressed for hydrostatic and Froude-Krylov forces by repanelling the hull up to the instantaneous waterline at each time-step.
Keywords
Head seas;Panel methods;Time domain;Surge
Report Number
DREA-CR-93-463 — Contractor Report
Date of publication
01 Sep 1993
Number of Pages
83
DSTKIM No
94-03035
CANDIS No
142287
Format(s):
Hardcopy;Originator's fiche received by DSIS

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