Ship Wave Scattering in Marina Environments

Ship waves and their effects has been the subject of a large number of studies. In particular, multiple scattering due to the ship's waves in a marina, can cause significant damage to marina structures. The science of ship wake generation and propagation is well advanced, but the methodologies of wake modeling in the real bathymetry are less developed. Numerical models have recently been developed and show reasonable results for representing the wake-wave fields. However, these codes require large computer resources, such as massive parallel processors or super computers. In this study, therefore, a simple model has been developed by using a mild-slope equation of a hyperbolic type. The mild-slope equation model calculates refraction, reflection, shoaling, breaking, and bottom friction of weakly irregular waves. The wake conditions generated along the vessel hull are used as sources for the numerical model and are estimated by field measurements or empirical equations. The scattering of water waves by floating or permeable marina structures is solved by a simple plane wave method in which scattering terms are added to the traditional mild-slope equation without inclusion of evanescent modes. Evanescent modes are only considered in predicting the reflection ratio against a permeable barrier and energy losses due to vortex shedding from its lower edge. The present model is verified with analytical solutions for the performance test and is applied to a planned marina port located in the northwest corner of Busan North Harbor.