Study On Applications Of Numerical Simulation Of Island-Reef Wave Fields

The special terrain near island-reef has particular influence on wave propagation which differs from open seas. From the mechanics view, the structure of sea beds near island-reef in the South China sea is especially complex. During the propagation from far-field in deep waters to near-island in shallow ones, waves could go through some dynamic changes like refraction, reflection, diffraction and breaking under the effect of topography, depth of water, island, etc. The wave environmental problem has became one of the most challenging engineering problems during the design of very large floating structure near island.The typical third-generation wave model WAVEWATCH-III ("WW3" for short) is chosen in this article for the study on applications of numerical simulation of island-reef wave fields. WW3 is a wave spectral model based on energy conservation. It can describe the variations of wave characteristics such as wave height, wave length and wave frequency, and it has been widely used since published. The second section of this article introduces the governing equations and its discrete methods as well as the parameter settings of WW3. The third section gives a 2-D case of regular waves'propagation under rapidly varying topography. The results show good accordance with the analytical solutions. The forth section and fifth section respectively gives an example of simulation about the process of far-field wave propagation to local-field through island-reef topography, individually using user-defined spectral and JONSWAP spectral as input. The calculation results are compared with results of physical model tests. The sixth section hindcast the wave fields near island caused by typhoon "haiou" and the numerical results has shown good accordance with the observed values. Comprehensive analysis shows that it is feasible to simulate the wave propagation under island-reef topography using WW3. It should be noted that picking up the proper wave spectral input and parameters of source terms contributes a lot to the simulation. This article provides references for WW3 use in engineering design.