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Coupled vessel and moonpool responses in regular and irregular waves

Abstract

Hydrodynamic coupling between the ship and moonpool responses is investigated. Dedicated experiments are carried out in the Ocean Basin at Sintef Ocean. Three different moonpool sizes are studied, where the moonpool length is 1/20, 1/10 and 1/2 of the ship length. The two former are square moonpools, while the latter is a rectangular moonpool with a width 1/2 of the ship’s beam. Numerical simulations are carried out using WAMIT. The coupling between the ship and moonpool is seen to be highly dependent on the volume of the moonpool relative to the submerged ship volume. WAMIT greatly over-predicts the moonpool responses in the proximity of resonance, which indicates that wave radiation damping is small, and that damping due to flow separation at sharp edges at the moonpool entrance is dominant. Two main nonlinear effects are observed; Swirling-type sloshing and secondary resonance. These nonlinear effects are excited in a range of wave periods where it is expected that a realistic sea environment will contain significant wave energy. This is most prominent in the largest moonpool. The piston mode shape in freely floating conditions is signficantly different relative to the one in forced heave.
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Category

Academic article

Language

English

Author(s)

  • Senthuran Ravinthrakumar
  • Trygve Kristiansen
  • Bernard Jean Marie Molin
  • Babak Ommani

Affiliation

  • SINTEF Ocean / Energi og transport
  • Aix-Marseille University
  • Norwegian University of Science and Technology

Year

2020

Published in

Applied Ocean Research

ISSN

0141-1187

Volume

96

Page(s)

1 - 15

View this publication at Norwegian Research Information Repository