Boundary layer dynamics in the swash zone under large-scale laboratory conditions
Boundary layer dynamics in the swash zone under large-scale laboratory conditions
复制标题
大尺度实验室条件下冲流区边界层动力学
DOI：
10.1016/j.coastaleng.2015.08.001
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发表时间：
2016-07
影响因子：
4.4
通讯作者：
Andrea Ruju;D. Conley;G. Masselink;M. Austin;J. Puleo;T. Lanckriet;D. L. Foster
中科院分区：
文献类型：
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作者：
Andrea Ruju;D. Conley;G. Masselink;M. Austin;J. Puleo;T. Lanckriet;D. L. Foster
本文介绍了一个实验室试验的结果，在一个粗砂障海滩冲激水动力学的泻湖背。边界层动力学分析使用高分辨率的近床速度测量声学多普勒速度剖面仪部署在冲流区。为了研究平均水动力模式，对冲刷事件进行了整体平均。一个建议的速度梯度标准允许识别的边界层增长的过程中的反渗透阶段，但它是无法表征边界层的变化过程中上冲。跨岸速度剖面很好地代表了对数模型的大部分的整体平均冲洗持续时间。上升流和湍流估算的摩擦系数具有相同的数量级，在上升流期间与边界层增长相关的变化很大。动量积分法提供的床面剪应力比对数模型小，这一结果可能与动量积分法中的假设有关，也可能与上冲过程中边界层厚度的低估有关。摩擦系数随雷诺数的增加而减小。这种行为是一致的传统的结果，稳定和均匀流在过渡区。
This paper presents the results of a laboratory experiment of swash hydrodynamics on a coarse sand barrier beach backed by a lagoon. Boundary layer dynamics have been analyzed using the high-resolution near-bed velocities measured by Acoustic Doppler Velocity Profilers deployed in the swash zone. Swash events have been ensemble-averaged in order to study mean hydrodynamic patterns. A proposed velocity gradient criterion allowed identification of the boundary layer growth during the backwash phase, but it was unable to characterize boundary layer variability during uprush. Cross-shore velocity profiles were well represented by the logarithmic model for a large portion of the ensemble-averaged swash duration. Uprush and backwash logarithmic-estimated friction factors were of the same order of magnitude with a strong variability related to the boundary layer growth during the backwash. The momentum integral method provided smaller bed shear stresses than the logarithmic model, a result possibly related to either the assumptions involved in the momentum integral method or to an underestimation of the boundary layer thickness during uprush. A decrease of friction coefficients for increasing Reynolds numbers at the early backwash was observed. This behavior is consistent with traditional results for steady and uniform flows in a transitional regime.