Laboratory experiments using an artificial seagrass meadow modeled after Zostera marina measured the impact of following currents on meadow-induced wave decay as a function of the imposed current velocity Uc$U_{\mathrm{c}}$, wave velocity Uw$U_{\mathrm{w}}$, and wave Cauchy number Caw$C{a}_{\mathrm{w}}$, which is the ratio of hydrodynamic drag force to restoring force due to blade stiffness. For small wave-induced reconfiguration of individual seagrass blades (Caw<2000)$\left(C{a}_{\mathrm{w}}<2000\right)$ and Uc/Uw>0.5,$U_{\mathrm{c}}/U_{\mathrm{w}}>0.5,$ the addition of current enhanced reconfiguration, which decreased wave decay relative to pure wave conditions. In contrast, when the wave-induced reconfiguration was large (Caw>2000)$\left(C{a}_{\mathrm{w}}>2000\right)$, the addition of following current did not significantly enhance blade reconfiguration or impact wave damping. Due to canopy drag, the current velocity within the submerged meadow, U1$U_1$, was significantly smaller than the depth-averaged current Uc$U_{\mathrm{c}}$, and a better prediction of wave decay was achieved using U1$U_1$ as the relevant velocity. The measured wave decay validated predictions based on a modified Cauchy number, defined for combined waves and current and using the in-canopy velocity U1$U_1$. Practical assumptions to facilitate the prediction of wave decay in the field are discussed and validated.

中文翻译：

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海草草地在波流组合条件下的波浪阻尼

使用以Zostera marina为模型的人造海草草甸的实验室实验测量了跟随水流对草甸引起的波衰减的影响，作为施加的水流速度的函数üC$U_{\mathrm{c}}$, 波速üw$U_{\mathrm{w}}$, 和波柯西数C一个w$C{a}_{\mathrm{w}}$，这是由于叶片刚度引起的流体动力阻力与恢复力的比值。用于单个海草叶片的小波诱导重构( C一个w< 2000 )$\left(C{a}_{\mathrm{w}}<2000\right)$和üC/üw> 0.5 ,$U_{\mathrm{c}}/U_{\mathrm{w}}>0.5,$添加电流增强的重构，相对于纯波条件减少了波衰减。相反，当波引起的重构很大时( C一个w> 2000 )$\left(C{a}_{\mathrm{w}}>2000\right)$，添加跟随电流并没有显着增强叶片重构或冲击波阻尼。由于冠层阻力，淹没草甸内的当前速度，ü1$U_1$, 明显小于深度平均电流üC$U_{\mathrm{c}}$，并且使用以下方法可以更好地预测波衰减ü1$U_1$作为相关速度。测量的波衰减验证了基于修改的柯西数的预测，定义为组合波和电流并使用冠层内速度ü1$U_1$. 讨论和验证了有助于预测现场波衰减的实际假设。