Observation and numerical modeling of tidal dune dynamics
Observation and numerical modeling of tidal dune dynamics
复制标题
潮汐沙丘动力学的观测和数值模拟
DOI：
10.1007/s10236-018-1141-0
复制
发表时间：
2018
期刊：
影响因子：
2.3
通讯作者：
T. Garlan
中科院分区：
文献类型：
--
作者：
Arnaud Doré;P. Bonneton;V. Marieu;T. Garlan
在法国西南部的阿卡春潮汐入口观测了两次潮汐周期的潮汐沙丘动力学。部署了一系列仪器来测量沙丘剖面的水深和电流变化。在此基础上，沙丘顶的水平和垂直位移被量化，并显示出与潮流相对应的重要动态。我们观察到沙丘侧面和正面的叠加波纹，随着潮流的逆转而迁移和改变极性。采用二维RANS数值模型模拟了潮流作用下平坦非粘性沙床的形态动力学演化过程。该模型再现了床层的演化过程，直到获得与观测到的叠加波纹在几何尺寸和动力学方面相当的砂床层场。然后将该模型应用于模拟与原位观测沙丘大小相似的大型沙丘场的动力学。在这两种情况下，模拟结果在定性和定量上都与测量结果相比较。该研究有助于更好地理解潮汐沙丘和叠加纹波形态动力学，并为利用数值模型预测其演变开辟了新的视角。
Tidal sand dune dynamics is observed for two tidal cycles in the Arcachon tidal inlet, southwest France. An array of instruments is deployed to measure bathymetric and current variations along dune profiles. Based on the measurements, dune crest horizontal and vertical displacements are quantified and show important dynamics in phase with tidal currents. We observed superimposed ripples on the dune stoss side and front, migrating and changing polarity as tidal currents reverse. A 2D RANS numerical model is used to simulate the morphodynamic evolution of a flat non-cohesive sand bed submitted to a tidal current. The model reproduces the bed evolution until a field of sand bedforms is obtained that are comparable with observed superimposed ripples in terms of geometrical dimensions and dynamics. The model is then applied to simulate the dynamics of a field of large sand dunes of similar size as the dunes observed in situ. In both cases, simulation results compare well with measurements qualitatively and quantitatively. This research allows for a better understanding of tidal sand dune and superimposed ripple morphodynamics and opens new perspectives for the use of numerical models to predict their evolution.