On the Application of Advanced Wave Analysis in Shallow Water Model Testing (Wave Splitting)

The HAWAI JIP originated from the observed differences between model tests and numerical simulations in shallow water. These differences were identified as being caused by spurious free waves and reflected waves in the model basin. Identifying these waves and incorporating them in the numerical simulations greatly improved the agreement between the model test results and the simulation results. Although the effect of spurious waves is also present in deep water, the effect is most profound in shallow water. The research therefore focused on shallow water, further refinement of wave identification, the background and theory behind spurious free waves, the effect of these waves on the motions of a LNG carrier and the occurrence of free waves in reality. In order to identify the different types of wave systems in a model basin a wave splitting (or separation) technique has been developed. This paper describes the current state-of-the-art of wave splitting and its limitations. Results are presented in the form of motion statistics of an LNG carrier that is moored in 15 m and 30 m water depth. The model tests results are compared with simulation results with and without the wave splitting methodology.