Numerical investigation of wave forces on two side-by-side non-identical boxes in close proximity under wave actions

Wave forces on two side-by-side non-identical boxes in close proximity under wave actions are investigated by employing a numerical wave flume based on the OpenFOAM® package. The similarity and discrepancy of hydrodynamic behavior between the wave response in the narrow gap and the wave forces on the boxes are the focus of the present study. Around resonant frequencies, the large-amplitude piston-type free surface oscillation in the narrow gap can lead to the peak values in the horizontal and vertical wave forces on the downstream box, and the horizontal wave forces on the upstream box. However, only a rapid decrease with the incident wave frequencies can be observed for the vertical wave forces on the upstream box. The resonant frequencies of the wave forces on two boxes are also different with those of wave response in the narrow gap. With the increase of incident wave amplitude, the resonant frequencies and normalized amplitudes of wave forces on downstream box tend to be smaller, which is similar with that of wave response in the narrow gap. However, the normalized wave forces on the upstream box around resonant frequencies do not always decrease with the increase of incident wave amplitude. On the whole, the hydrodynamic behavior of wave forces has some similar characteristics with that of wave response in the narrow gap. However, evident discrepancy between them can also be observed because the other factors, such as the wave response upstream and downstream the two-box systems, also has the non-negligible contribution to wave forces.