In the marine engineering field, a sound wave is often utilized to visualize objects. In such a sensing method, an accurate numerical prediction of sound propagation is an important issue for theoretical considerations. Recently, a finite difference method in time domain (FDTD) is often applied to wave propagation. However, an existing FDTD sometimes fails to match the accuracy to be required. In the present paper, strategies to improve conventional methods are presented: the application of the compact finite difference on staggered grid with adjusted coefficients and the usage of optimized multistep time integration. It is shown that through these tactics, a highly accurate simulation is attainable.

No abstract

No abstract

No abstract

This study focuses on the hydrodynamics in the opening of artificial reefs and the applicability of a quasi-three dimensional nearshore current model with the wave-current interaction. First, the characteristics of the waves and steady currents in the opening area were investigated using the wave flume under irregular wave conditions. Secondly, the numerical model was calibrated and verified by comparing with the experiment results. Finally, the numerical model was applied to the results of a field investigation conducted at Uradome Beach in Tottori, Japan. The computed wave and steady current fields in the opening of two artificial reefs were compared with the measured data. From the computed results, we found that the numerical model gives reliable results to the prediction of the hydrodynamics around the artificial reefs.