A numerical study of a freely floating lifeboat in regular waves

Chen, H, Qian, L, Ma, Z, Causon, D and Mingham, C (2018) A numerical study of a freely floating lifeboat in regular waves. In: International Offshore and Polar Engineering Conference, 10 June 2018 - 15 October 2018, Sapporo, Japan.

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Abstract

Copyright © 2018 by the International Society of Offshore and Polar Engineers (ISOPE) In the present paper, the open source toolbox OpenFOAM was applied for analysis of the hydrodynamic force and motion of a floating lifeboat in regular waves. The Reynolds averaged Navier-Stokes (RANS) equations were solved and the free surface tracking was achieved by using the volume of fluid method. An overset mesh method was applied for the moving boundary of the lifeboat, in which a body-fitted mesh was generated around the lifeboat using the utility snappyHexMesh and a hexahedral background mesh was produced by the utility blockMesh. The field values were interpolated in the overlapping area between these two layers of meshes. The hydrodynamic forces and the motion of the lifeboat were calculated under the condition that the lifeboat was off-centered in the wave flume to mimic the effects of a larger mother ship. Due to the unsymmetrical condition, full six-degree of freedom (DOF) motion needs to be taken into account. The predicted hydrodynamic force and surface elevation for the fixed lifeboat, and the six DOF motion of the lifeboat were compared to the experimental data. Satisfactory agreement was achieved except the roll moment and motion, for which large discrepancies were observed.