Modeling the hydrodynamics and morphodynamics of sandbar migration events
Modeling the hydrodynamics and morphodynamics of sandbar migration events
复制标题
DOI：
10.1016/j.coastaleng.2021.103885
复制
发表时间：
2021-03
影响因子：
4.4
通讯作者：
Y. Rafati;T. Hsu;S. Elgar;B. Raubenheimer;E. Quataert;A. V. van Dongeren
中科院分区：
文献类型：
--
作者：
Y. Rafati;T. Hsu;S. Elgar;B. Raubenheimer;E. Quataert;A. V. van Dongeren
许多模型可用于科学和工程目的，数值模拟近岸流体动力学和相应的形态演变。然而，这些模型在需要校准的物理过程的参数化中包括可调整的系数，因此通过包括额外的物理学仍然有改进的空间。其中一个模型是XBeach，它可以模拟风暴期间的侵蚀，并根据观测结果进行适当的校准。模拟的泥沙输运，特别是在跨岸方向，是敏感的可调系数，与网站和事件的具体首选值。在这里，技能的X海滩进行了调查，通过比较1维（跨岸）的深度平均模拟与观察的波浪，电流，和沙洲迁移横跨大西洋海滩。系数的校准提高了协议的计算结果与观测到的波高，离岸指向的平均电流（回流），波轨道速度的第三个时刻（偏斜和不对称），和陆上/海上沙洲迁移，虽然建议的系数值取决于所使用的参数化。例如，包括可变破碎波滚柱能量模型导致比使用默认常数系数值更熟练的底流预测。使用校准的辊系数和相应的底流，XBeach模拟所观察到的离岸迁移的沙洲。在XBeach的陆上运输是由非正弦波轨道速度驱动的，建议的系数值取决于用于估计偏度和不对称性和相关的运输，以及入射波条件的参数化。XBeach计算的跨海岸输沙率进行了比较，通过一个常用的输沙公式的基础上，实验室实验的估计。相互比较表明，使用比默认值大3或4倍的波浪引起的陆上运输参数可以至少部分地补偿XBeach中底部边界层流驱动陆上运输的缺乏。
A number of models are available for science and engineering purposes that numerically simulate nearshore hydrodynamics and the corresponding morphological evolution. However, the models include adjustable coefficients in parameterizations for physical processes that need to be calibrated, and thus there remains room for improvement by including additional physics. One such model is XBeach, which can simulate erosion during storms with proper calibration based on observations. The modeled sediment transport, especially in the cross-shore direction, is sensitive to the adjustable coefficients, with preferred values that are site and event specific. Here, the skill of XBeach is investigated by comparing 1-dimensional (cross-shore) depth-averaged simulations with observations of waves, currents, and sandbar migration across an Atlantic Ocean beach. Calibration of coefficients improved the agreement of the computed results with observed wave heights, offshore-directed mean currents (undertow), the wave-orbital-velocity third moments (skewness and asymmetry), and onshore/offshore sandbar migration although the proposed coefficient values depend on the parameterizations used. For example, including a variable breaking-wave roller energy model resulted in more skillful predictions of undertow than using the default constant coefficient value. Using the calibrated roller coefficients and corresponding undertow, XBeach simulated the observed offshore migration of the sandbar. Onshore transport in XBeach is driven by non-sinusoidal wave-orbital velocities, and proposed values for coefficients depend on the parameterization used to estimate skewness and asymmetry and the associated transport, as well as on incident wave conditions. XBeach calculations of cross-shore sediment transport rates were compared with those estimated by a commonly used sediment transport formula based on laboratory experiments. The inter-comparison suggests that using a wave-induced onshore transport parameter 3 or 4 times larger than the default value may at least in part compensate for the lack of bottom-boundary-layer-streaming-driven-onshore transport in XBeach.