Performance Comparison of Spectral Wave Models Based on Different Governing Equations Including Wave Breaking

Abstract

The performance of three spectral wave models based on different types of governing equations, REF/DIF S, MIKE 21 BW module, and SWAN, was compared by using four laboratory or field experimental data sets. The comparison was focused on accurate prediction of measured wave heights. Characteristics of the three wave models were discussed and their overall predictability of the measured data was evaluated by calculating mean absolute relative errors of wave height. All the numerical models simulated fairly well shoaling and breaking of waves propagating on a plane sloping beach, but the model accuracy was somewhat degenerated in simulating waves propagating over a barred beach. Among the three models, MIKE 21 BW was the most insensitive to the bathymetric change. Combined refraction-diffraction over a shoal without breaking was quite well simulated by the models, especially by REF/DIF S and MIKE 21 BW. When waves break over the shoal, however, all the models failed to reproduce the wave field behind the shoal. The agreement with data in simulating wave diffraction around breakwater was remarkably good for MIKE 21 BW, but poor for other two models. Except the last simulation, the mean absolute relative errors of wave height from the three models ranged between 3 and 27%.