Attenuation of Nonlinear Waves by Rigid Vegetation: Comparison of Different Wave Theories

作者：Zhu Ling; Chen Qin^*

来源：Journal of Waterway Port Coastal and Ocean Engineering-ASCE, 2017, 143(5): 04017029.

DOI：10.1061/(ASCE)WW.1943-5460.0000415

• Wave attenuation
• Vegetation
• Energy flux
• Energy dissipation
• Wave theories
• In-canopy velocity

This study investigates the performances of theoretical wave attenuation models in predicting vegetation-induced wave decay. The existing theoretical models are all based on linear wave theory, which cannot describe nonlinear waves accurately. This study applies Stokes second-order and cnoidal wave theories to solve the energy balance equation for wave height evolution. Results from a phase-resolving numerical model serve as reference solutions. A total of 30 tests are devised for shallow-intermediate water waves through emergent and submerged vegetation. The differences between theoretical and numerical model results (epsilon(H)) and between linear and nonlinear-based theoretical model results (Delta H) are quantified. The test results show that for wave propagation through emergent vegetation Delta H is <= 6% and epsilon(H) is <= 5%, whereas over submerged vegetation, epsilon(H) reaches as large as 25%. With a 5% tolerance of epsilon(H), linear-based theoretical models remain valid for emergent cases and submerged cases with a small Ursell number (<= 30 in this study). This work has found that the inability of theoretical models to simulate the in-canopy velocity reduction and nonlinear wave-wave triad interactions contributes to the large epsilon(H) in submerged cases.

• 出版日期2017-9