Intrawave observations of sediment entrainment processes above sand ripples under irregular waves
Intrawave observations of sediment entrainment processes above sand ripples under irregular waves
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DOI：
10.1029/2010jc006216
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发表时间：
2011
影响因子：
--
通讯作者：
R. Murray;P. Thorne;D. Hodgson
中科院分区：
文献类型：
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作者：
R. Murray;P. Thorne;D. Hodgson
[1]报道了在大型水槽设施中产生的不规则波浪下波纹上的波内沉积物夹带过程的测量。这些资料包括在不规则波浪强迫下以高时空分辨率收集的小尺度过程的实质性观测资料，典型的沿海环境。声波测量了水流速度、河床形态以及平面和波纹河床上悬浮沉积物的浓度。在每次波纹床实验中，测量陡边波纹的波峰，认为在波峰以上可能发生流动分离。在波峰之上，近床悬浮物的波内变化强烈，表明漩涡的形成和脱落，在轨道直径大于1.2倍波纹波长l的波浪半周期中占主导地位。不规则波的参数化具有显著的波高Hs和显著的轨道直径d0s。因此，在不规则波浪条件下，在d0s/l > 1.2的陡峭波纹上，旋涡脱落被认为是主要的泥沙夹带过程。此外，观察到旋涡脱落的波半周期百分比为26 d0s/l。这些结果表明，在不规则波浪下，存在一个明确的悬浮沉积物结构，与先前在规则波浪下观察到的涡落一致。引用本文：O 'Hara Murray， R. B.， P. D. Thorne和D. M. Hodgson(2011)，不规则波浪下沙纹以上沉积物携沙过程的波内观测，J. Geophys。研究，116,C01001, doi:10.1029/2010JC006216。
[1] Measurements of intrawave sediment entrainment processes are reported above ripples under irregular waves generated in a large‐scale flume facility. The data consist of substantive observations of small‐scale processes collected at high spatial and temporal resolution under irregular wave forcing, typical of coastal environments. Acoustic measurements were made of water velocities, bed forms, and suspended sediment concentration over plane and rippled beds. During each rippled bed experiment, measurements were taken over the crests of steep sided ripples, above which flow separation was considered likely to occur. Above the ripple crests, a strong intrawave variation in the near‐bed suspended sediment, indicative of vortex formation and shedding, was observed to dominate wave half cycles where the orbital diameter was greater than 1.2 times the ripple wavelength l. The irregular waves were parameterized with a significant wave height Hs and a significant orbital diameter d0s. Thus, during irregular wave conditions and over steep ripples where d0s/l > 1.2, vortex shedding was deemed as the dominant sediment entrainment process. Furthermore, the percentage of wave half cycles where vortex shedding was observed, was found to scale as 26 d0s/l. These results demonstrate, for under irregular waves, the existence of a clear suspended sediment structure consistent with vortex shedding, previously observed under regular waves. Citation: O’Hara Murray, R. B., P. D. Thorne, and D. M. Hodgson (2011), Intrawave observations of sediment entrainment processes above sand ripples under irregular waves, J. Geophys. Res., 116, C01001, doi:10.1029/2010JC006216.