Experimental and numerical investigation of wave-induced dynamics of emergent flexible vegetation

Abstract

Understanding and modeling the dynamics of flexible vegetation is fundamental to investigating wave attenuation by flexible vegetation, which is fast becoming an essential issue in nature-based coastal defense. Existing studies are mainly restricted to submerged vegetation and linear wave assumptions. Hence, a new mechanical model for simulating wave-induced emergent flexible vegetation dynamics is developed by considering the dynamic variation of the submergence ratio. A set of wave flume experiments on emergent flexible vegetation dynamics driven by waves are conducted. The reliability of the developed model is revealed based on a series of model validations. Experimental data indicates that emergent flexible vegetation dynamics are influenced by the Ursell number, Cauchy number, Excursion ratio, stiffness-to-force ratio, Keulegan–Carpenter number, and Reynolds number. Simulation results also demonstrate the usefulness of the emergent flexible vegetation dynamic model. There is a considerable difference in simulated horizontal force and stem postures regarding emergent flexible vegetation between the previous submerged flexible vegetation dynamic model and the developed new emergent flexible vegetation dynamic model. The results from this study optimize the simulation theory and method of wave-induced flexible vegetation dynamics, and generate new insights into the interaction between coastal flexible vegetation and waves.