IMPLEMENTATION OF VISCOELASTIC MUD-INDUCED WAVE DISSIPATION IN SWAN

The absence of wave-mud interaction in wave models forced researchers to calibrate their models by increasing sand friction coefficient in the model. However; thisapproach would result in more dissipation in low-frequency part of the spectrum while the field observations designate more damping in high-frequency part of the spectrum. To remedy this problem, researchers were persuaded to include the correct mechanism in the models[1]. Mud-induced relative dissipation was implemented for first time in SWAN model and validated for Guyana coast. Generally two important results were found: (1) large wave height existed in the absence of mud-induced relative dissipation in model results; and (2) the mean wave period decreased strongly over the fluid mud layers, due to strong dissipation of the low-frequency waves[2].In some field cases lack of in situ data forced researchers to do inverse modeling, i.e. to choose values for unknown data such that model outputs were more compatible with observations[3]. This approach was performed on Casino beach, Brazil. It was shown that wave height was overestimated if wave-mud interaction was ignored. Itproved mud existence in the region. Then, they considered 40 cm thickness for mud layer over the region. Inclusion of wave-mud interaction mitigated the overestimation in wave height but using a uniform 40 cm mud thickness resulted in high mud-induced dissipation, and they concluded that patchy mud layer exist in some points in this region[3].