Wave transformation model to predict wave characteristics
To assess the wake impact in exposed coastal areas and shallow water environments, we have developed a computational efficient and robust method which has been used in numerous projects. The method is based on the Spectral Wave (SW) module of MIKE Powered by DHI’s 2D modelling software MIKE 21. The model is based on a phase-averaged energy conservation approach. This modelling technique has the advantage of being applicable even to large coastal areas. The model includes the effects of wave refraction and shoaling due to varying depth and currents, as well as energy dissipation due to bottom friction and wave breaking. Even though this wave transformation model neglects the transient effect of the ship waves, it predicts the spatial variation of characteristic wave heights, wave periods and wave directions in large domains – thereby describing the strength or severity of the wake wash in shallow water.
Model simulation with computational fluid dynamics and MIKE 21 SW
Wave transformation modelling was carried out to investigate the transformation of wake waves generated by a 334 m tanker and a 45 m tug travelling towards the shore at selected locations – Kitkiata Inlet in the Douglas Channel and at Dixon Island in Principe Channel in British Columbia.
The modelling included simulations for a loaded VLCC and for tugs. The waves generated by the vessels were modelled by FORCE Technology using Computational Fluid Dynamics (CFD) modelling, and the wave transformation towards the shore was modelled by MIKE 21 SW.
For comparison of the estimated wake waves with the wind-generated waves, a model study of the wind-generated waves was also conducted, where the wave conditions for the relevant wind speeds and directions were estimated.