MODELLING RECURRENCE MOTION OF A LARGE VOLUME SEMI- SUBMERSIBLE

Abstract

This paper presents a modelling reccurence motion on a large volume semi-submersible using ANSYS AQWA version 13. Recurrence is the phenomenon in which a system of quasi-periodically returns to its initial conditions after undergoing some degrees of evolution, this finding supports the theory of to quasi determinism (QD) of sea waves. The computational method calculated the hydrodynamic characteristics and recurrence motion for the semi-submersible. The motions were analyzed in four types of different incident irregular waves by using JONSWAP Spectrum which is generally regarded as a pure randomness in nature interacting with the structure generating hydrodynamic motion. Responses of motion were simulated for 3 hours, in which it was divided into 9 seeds for each incident wave. The incident waves of significant wave height of Hs 7 meters with the wave periods of Tp 12.7 and 13.5 seconds; and significant wave height of Hs 8 meters with the wave periods of Tp 12.7 and 13.5 seconds were generated in the simulation, it was found that the recurrence motion occurred in the time interval (to + 635s, to + 879s) and (to + 1774s, to + 1988s); (to + 693s, to + 882s) and (to + 1735s, to + 1924s); (to + 693s, to + 882s) and (to + 1735s, to + 1924s); (to + 792s, to + 992s) and (to + 1938s, to + 2138s) respectively. Recurrence motion on a large volume semisubmersible supports the quasi determinism (QD) Theory.