Coupling dynamics of gap resonance and heave motion of floating box in front of a fixed box

Coupling dynamics between wave resonance in the narrow gap and heave motion of floating box in a heave-fixed-boxes system is investigated. The two peaks of the heave motion amplitudes and free surface amplitudes are identified as the first and second resonant frequencies according to the theoretical analysis based on potential flow model. The first and second resonant frequencies have the in-phase and out-of-phase modes, respectively, which can be confirmed by a new approach of free decay test. The radiation damping is important at the first resonant frequency with in-phase mode; while the viscous damping is indispensable at the second resonant frequency with out-of-phase mode.