Fluid resonance in the narrow gap for a box close to a bottom-mounted wall with permeable bed

The behavior of fluid resonance in a narrow gap formed between a ship and a wharf on a permeable bed is investigated by using a two-dimensional viscous numerical model based on OpenFOAM package. The influence of the permeable bed is significant in the region of low-frequency and resonant frequency ranges, where the decreased free surface amplitude in the narrow gap can be observed, especially for large box draft and large porosity. The increased effect of permeable bed can be generated by large bed thickness and small bed width. With the increase of incident wave amplitude, the influence of permeable bed gives rise to weak. All of these phenomena can be explained by the variation of the fluid entering the seepage surface, where the large vertical velocity and more fluid volume entering the permeable bed can be computed for the cases of larger permeable bed effect. Finally, the variation tendency of wave forces on the box and the wall is consistent with that of wave amplitude in the narrow gap.