Numerical Examination of Wave-induced Coupling Roll Motion and Fluid Resonance between twin Floating Barges in Proximity

Abstract

Coupling effects of roll motion and fluid resonance between twin rectangular barges subjected to incident waves normal to the spanwise of the narrow gap are investigated employing a two-dimensional numerical wave flume based on a CFD package OpenFOAM. The governing equations for the fluid flow are the Navier-Stokes equations of incompressible Newtonian fluid. The interface between water and air phases is captured by a VOF (volume of fluid) method. The fluid-structure interaction (FSI) is treated with moving meshes in the Arbitrary Lagrangian-Eulerian frame. The present numerical model is validated against wave generation and propagation over a flat bed and the decay of a free rolling rectangular barge in still water. The comparisons with available numerical results show that the present numerical wave flume works well. It is then used to investigate the roll response of the twin floating barges in proximity. The numerical results of this work show that the resonant frequency of the fluid oscillation in the narrow gap between twin rolling barges is smaller than that between twin fixed barges. However, the resonant wave height in the gap between twin rolling barges is observed to be in the same magnitude as that between twin fixed barges. Moreover, the present numerical results indicate that the maximum rolling amplitudes of the twin barges are close to each other, and they appear at the same resonant frequency of the fluid oscillation in the narrow gap. At the low frequency band, the amplitude of the rear barge is larger than that of the leading one. Otherwise, in the frequency band higher than the resonant conditions, the leading barge has a larger response. The present numerical solutions also suggest that the twin barges roll in anti-phase.