Effects of wave nonlinearity on submerged flexible vegetation dynamics and wave attenuation

Dynamic characteristics and wave attenuation mechanism of flexible vegetation have propelled to the forefront in investigations of coastal engineering. Given that existing studies of wave nonlinearity are mainly restricted to rigid vegetation assumptions, this study was undertaken to quantitatively determine the effect of wave nonlinearity on submerged flexible vegetation dynamics as well as wave attenuation based on flexible vegetation dynamic model and experimental results. Meanwhile, the influence of different wave theories along with different determination methods of characteristic wave velocity was evaluated quantitatively. Results reveal that wave nonlinearity exerts substantial nonlinear and nonmonotonic effects upon flexible vegetation dynamics and wave attenuation rate. The maximum horizontal force, stem tip excursion, and wave height attenuation rate increase as the dimensionless Ursell number increases on the whole under the present investigation conditions. Moreover, it is suggested that different wave theories and determination methods of characteristic wave velocity can result in slight discrepancies of flexible vegetation dynamics, which may further affect wave attenuation by flexible vegetation. Determining the impacts of wave nonlinearity, wave theory, and characteristic wave velocity provides clearer insight into the wave attenuation mechanism of flexible vegetation, which is of great benefit to the flexible vegetation dynamics and related wave attenuation model improvement. •Wave nonlinearity exerts nonlinear and nonmonotonic effects upon flexible vegetation dynamics and wave attenuation rate.•The maximum horizontal force, stem tip excursion, and wave attenuation increase as the Ursell number increases on the whole.•Different wave theories and determination methods of characteristic wave velocity can affect flexible vegetation dynamics.