This paper applies our in-house solver, naoe-FOAM-SJTU to simulate the seakeeping problem of two ships in side-by-side configuration. The physical models are chosen as a barge and a geosim, exposed in regular head waves with gap equals to 0.1m. The geosim set heave and pitch motions free and the barge is fixed. This configuration can keep the distance of gap constant, which contributes to simulate the gap flow. The gap wave elevation is compared to existing results and shows well agreement. CFD method can avoid overestimate due to existence of viscosity. The gap flow model is discussed as well as motion and forces of geosim is calculated.
In recent years, the studies about multi-body system become popular, especially for vessels which transport and storage deep sea resources like FPSO or FLNG. The offloading process happens between FPSO and shuttle tanker receiving much attention due to its practical application. For the problem of side-by-side, the hydrodynamic performance of floating body will be influenced by the other floating body. The multi-body interaction effect will change the body motion as well as forces and moments on floating body. Since the gap between two floating bodies in offloading process becomes close, the collision risk and gap effects are challenging problems worth to be solved. The gap effect happens when two floating bodies are in side-by-side configuration, the wave elevation in gap may show different modes. The mode shapes of wave elevation are similar to that happens in moonpools (Molin, 2001).
Side-by-side configuration problems involving gap effect have been studied in recent years. Huijsmans et al (2001) developed a robust linear potential theory on side-by-side system. Lewandowski (2008) applied boundary element methods both on 2-D and 3-D condition. The free surface in the gap which between two floating bodies is discussed, showing profound effect on hydrodynamic forces. Fournier et al (2006) performed experiments for variable distances and used diffraction packages to do the numerical tests. The numerical tests were about wave resonance in gap, and results of hydrodynamic interaction were compared with experiments. Clauss et al (2013) integrated damping lid and introduced WAMIT to focus on wave fields in gap. Molin et al (2002) simulated the gap flow and wave propagation between the barge and ice sheet. The wave elevation and decay in gap was tested in experiment. Watai et al (2015) performed Rankine panel method on a benchmark case, brought improvement to the numerical convergence to this method. The side-by-side configuration is applied and the gap flow model is simulated.