Improvement Of MASNUM-WAM And Its Parameter Adjustment

MASNUM ocean wave numerical model is one of the most advanced thirdgeneration wave model, and it has been extensively used in both numerical simulationof waves in China seas and ocean engineering. But recently, the results based on largeamounts of numerical experimentations and engineering calculations indicate that inlow wind speed conditions, the significant wave height simulated with theMASNUM-WAM is lower than practical. In order to solve these problems, this paperfirstly looks back into the progress of ocean wave spectrum research so as to providereliable theoretical basis and inspection standard for the improvement and parameteradjustment. Latter we establish an experimental model for the MASNUM-WAM andpass the contrast, verify the effectiveness of this model. Thus it becomes a convenientand reliable platform for the further experimentation. Based on the experimentalmodel, we firstly reassess the distribution of the wave number space and thecalculation time step. Then it is found that the problem of significant wave heightsimulated with the MASNUM-WAM is lower than practical in low wind conditions isdue to the limitation of spectral component growth via numerical experimentation. Anew grow limiter based on the scale invariance law is suggested and improves themodel substantially in the case of low wind speed. Even so, there are problems insimulating the fully developed sea. Therefore a further numerical study of theparameters of the dissipation source function of MASNUM-WAM is done. The resultsshows that the two parameters of the dissipation source function should not take asconstants, but as a function of the upper wind speed, then a fitting relationship isgiven. Comparison before and after the change shows that the use of new parametersof the dissipation source function can improve the model in simulating fullydeveloped sea.