NUMERICAL MODELING OF THE INTERACTIONS BETWEEN NONLINEAR WAVES AND ARBITRARILY FLEXIBLE VEGETATION

Coastal wetlands are among the natural features with the capability to dissipate wave energy and reduce storm damage. Inadequate representation of wave and vegetation characteristics in numerical models may reduce their capability in predicting wave processes over wetlands. Previous numerical wave models have typically applied simplifications on vegetation behavior. For instance, vegetation stems were usually assumed to be rigid or semi-flexible and thus extreme stem deflections could not be captured. In this study, a time-domain nonlinear numerical model based on extended Boussinesq formulation is developed and coupled with a numerical model for vegetation blade dynamics that allows for arbitrary flexibility. Comparison with analytical and laboratory experiments show that the coupled model can adequately predict flow as well as vegetation blade dynamics without the need for any parameter tuning. The model is then used to obtain wave-induced forces on a stem and vegetation blade orientation. Model results indicate that the variation of the vegetative drag coefficient with wave frequency is non-monotonic.