Effects of Entrance Loss on Harbor Oscillations

By assuming a head loss across the harbor entrance the wave-induced response in a rectangular model harbor is studied theoretically. The loss is assumed to be quadratic in local velocity with a constant friction coefficient. Bottom and side-wall dissipation are not considered. It is shown that odd higher harmonics are present. The resonance characteristics of the fundamental harmonic response in the harbor are significantly influenced by the additional damping due to friction, especially for the lowest peaks. While in the perfect fluid theory these peaks heighten with diminishing entrance width, in the presence of friction the opposite is true for sufficiently narrow mouth.