Development of bedforms due to waves blocked by a counter current
Development of bedforms due to waves blocked by a counter current
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由于逆流阻挡波浪而形成河床形态
DOI：
10.1002/esp.4577
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发表时间：
2018
影响因子：
3.3
通讯作者：
K. Sarkar
中科院分区：
文献类型：
--
作者：
D. Chatterjee;S. Ghosh;B. S. Mazumder;K. Sarkar
本文在实验室水槽中进行了有泥沙床单向流中表面波传播的实验研究。本文介绍了通过适当调节的均匀流体流和反向传播波的波阻现象引起的底形的空间变化。通过在特定流量中找到波被有效阻挡的临界波频率来确认波阻挡的发生，并使用线性色散关系建立。这项工作的目的是确定波浪阻塞及其对沉积物床面上床形发展的影响。有趣的是，在三个区域的底形过渡处观察到了底形特征，不对称的波纹具有由来流引起的更陡的斜坡下游面，其次是波浪阻挡区下方的平坦沙洲和下游波浪主导区下方的更对称的波纹。这种现象表明，沉积物床被分割成三个不同的区域床的几何形状沿着流动。给出了沿着非均匀流在沉积物床面上的平均流、雷诺应力、湍动能和功率谱密度的偏差。文中还讨论了底切应力、床面粗糙度和床形特征的随机性。这些结果对于关心现代过程的工程师和地球科学家以及那些对从化石底形解释古环境条件感兴趣的人都是有意义的。© 2019约翰威利父子有限公司
Experiments are conducted in a laboratory flume on the propagation of a surface wave against unidirectional flow with a sediment bed. This article presents the spatial variation of bedforms induced by the wave‐blocking phenomenon by a suitably tuned uniform fluid flow and a counter‐propagating wave. The occurrence of wave‐blocking is confirmed by finding a critical wave frequency in a particular flow discharge in which the waves are effectively blocked and is established using the linear dispersion relation. The purpose of this work is to identify wave‐blocking and its influence on the development of bedforms over the sediment bed. Interestingly bedform signatures are observed at a transition of bedforms in three zones, with asymmetric ripples having a steeper slope downstream face induced by the incoming current, followed by flat sand bars beneath the wave‐blocking zone and more symmetric ripples below the wave‐dominated region at the downstream. This phenomenon suggests that the sediment bed is segmented into three different regions of bed geometry along the flow. The deviations of mean flows, Reynolds stresses, turbulent kinetic energy, and power spectral density due to the wave‐blocking phenomenon are presented along the non‐uniform flow over sediment bed. The bottom shear stress, bed roughness and stochastic nature of the bedform features are also discussed. The results are of relevance to engineers and geoscientists concerned with contemporary process as well as those interested in the interpretation of palaeoenvironmental conditions from fossil bedforms. © 2019 John Wiley & Sons, Ltd.