LAUSR

Abstract The hydrodynamic behavior of box-systems with and without narrow gaps is investigated by employing a numerical wave flume based on OpenFOAM® package. After the validation with available experimental data and simulating results in the literature, the related phenomena induced by the large-amplitude free surface oscillation in narrow gaps are examined. Numerical comparisons between the single- and two-box systems suggest that the fluid resonance in the narrow gap can significantly affect the behavior of box-system, including wave responses, hydrodynamic coefficients, and vertical wave forces of the box-system. Analogous phenomena can also be observed in three-box system at the fundamental natural frequency, which is generated by the in-phase free surface oscillations in narrow gaps. At the second natural frequency, only a little discrepancy in the results of wave responses, hydrodynamic coefficients, and total wave forces can be observed between two- and three-box systems. The wave forces on each box in three-box system are significantly affected by the wave resonance in two gaps, including the fundamental and second resonant frequencies.