ANALYSIS OF WIND-WAVES WITH SWAN ON STRUCTURED MESH AND UNSTRUCTURED MESH DURING THE ARRIVAL OF TYPHOON

抄録

 Currently, the estimation of wind-waves on coastal waters is commonly done in practice on structured mesh. However, when complex geometries arise (for instance, irregular coastlines, islands and breakwaters) multistage nesting with smaller grid spacing which entails high computational cost is required on structured mesh and even then it is sometimes difficult to get accurate bottom topographical approximation of only required areas. In contrast, since unstructured mesh can perform detailed geometrical approximation only at necessary places, it is expected to reduce the computational cost while securing the accuracy of the bottom topographical approximation.

 Hence, the objective of this study is to analyse wind waves with SWAN (Simulating WAves Nearshore) model, which is commonly used in practice for nearshore wave analysis, on structured mesh and unstructured mesh and, thereby to find out an effective approach to use SWAN model in future practice. The behaviour of SWAN model on structured mesh (ST-SWAN) and on unstructured mesh (UNST-SWAN) was analysed and advantages of UNST-SWAN over ST-SWAN were discussed. Wind-waves were estimated during the arrival of Typhoon with ST-SWAN and UNST-SWAN. Wind-wave characteristics obtained from both ST-SWAN and UNST-SWAN were basically consistent. Considering the advantages of UNST-SWAN, an effective approach to apply SWAN model in future practice by combining both structured and unstructured mesh where necessary was proposed during this study.