An analysis on the propagation of the instabilities of longshore currents using wavelet coherence spectrum

Ren Chunping; Liu Yu; Zhao Xiping

doi:10.12284/hyxb2021092

Volume 43 Issue 6

Jun. 2021

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Ren Chunping，Liu Yu，Zhao Xiping. An analysis on the propagation of the instabilities of longshore currents using wavelet coherence spectrum[J]. Haiyang Xuebao，2021, 43(6)：118–128 doi: 10.12284/hyxb2021092

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An analysis on the propagation of the instabilities of longshore currents using wavelet coherence spectrum

doi: 10.12284/hyxb2021092

College of Water Resource Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China

Received Date: 2020-06-04
Rev Recd Date: 2020-08-08

Available Online: 2021-07-08

Publish Date: 2021-06-30

Abstract

Abstract

The instabilities of longshore currents are the far infragravity band waves. The study of its propagation characteristics will help us to understand its influence on the evolution of coastal beach and the transport and migration of pollutants, fish eggs and other organisms. Based on the wavelet coherence spectrum, this paper analyzes the propagation characteristics of the unsteady motion under regular and random waves, and discusses the influence of the wave height, period and slope on it. The results show that the irregular wave is easier to induce the unsteady motion, and the positive or negative phase difference of the unsteady motion is about 30° in the case of irregular waves, which is similar to the incident angle of waves; with the increase of the incident wave height, nonlinear effects become stronger and the period range of the unsteady motion will be wider, that is to say, it is easier to induce the unsteady motion; the incident wave period has a little effect on the propagation; the steeper the slope is, the more likely it is to induce the instabilities of longshore currents.
- longshore current,
- unsteady motion,
- propagation,
- wavelet coherence,
- phase lag

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References

[1]	Shanks A L, Morgan S G, Macmahan J, et al. Persistent differences in horizontal gradients in phytoplankton concentration maintained by surf zone hydrodynamics[J]. Estuaries and Coasts, 2018, 41(1): 158−176. doi: 10.1007/s12237-017-0278-2
[2]	Bowen A J, Holman R A. Shear instabilities of the mean longshore current 1. Theory[J]. Journal of Geophysical Research, 1989, 94(C12): 18023−18030. doi: 10.1029/JC094iC12p18023
[3]	Özkan-Haller H T, Kirby J T. Nonlinear evolution of shear instabilities of the longshore current: A comparison of observations and computations[J]. Journal of Geophysical Research: Oceans, 1999, 104(C11): 25953−25984. doi: 10.1029/1999JC900104
[4]	Dodd N, Iranzo V, Caballería M. A subcritical instability of wave-driven alongshore currents[J]. Journal of Geophysical Research, 2004, 109(C2): C02018. doi: 10.1029/2001JC00106
[5]	Reniers A J H M, Battjes J A, Falqués A, et al. A laboratory study on the shear instability of longshore currents[J]. Journal of Geophysical Research: Oceans, 1997, 102(C4): 8597−8609. doi: 10.1029/96JC03863
[6]	Noyes T J, Guza R T, Feddersen F, et al. Model-data comparisons of shear waves in the nearshore[J]. Journal of Geophysical Research: Oceans, 2005, 110(C5): C05019. doi: 10.1029/2004JC002541
[7]	Ren Chunping, Zou Zhili, Qiu Dahong. Experimental study of the instabilities of alongshore currents on plane beaches[J]. Coastal Engineering, 2012, 59(1): 72−89. doi: 10.1016/j.coastaleng.2011.07.004
[8]	任春平, 蒋利君, 季海嘉. 沿岸流不稳定运动对边缘波影响的实验研究[J]. 中国科学: 技术科学, 2015, 45(4): 423−433. doi: 10.1360/N092014-00028 Ren Chunping, Jiang Lijun, Ji Haijia. A laboratory study of the effects of the instability of longshore currents on the edge waves[J]. Scientia Sinica Technologica, 2015, 45(4): 423−433. doi: 10.1360/N092014-00028
[9]	沈良朵. 缓坡沿岸流不稳定性特征研究[D]. 大连: 大连理工大学, 2015. Shen Liangduo. Study of the feature of longshore current and its instability on mild beach slope[D]. Daliang: Daliang University of Technology, 2015.
[10]	Ruiz-Merchán J, Otero L, Conde M, et al. Field observations of wave and current characteristics on a microtidal reflective beach[J]. Journal of Coastal Research, 2019, 35(6): 1164−1184. doi: 10.2112/JCOASTRES-D-18-00120.1
[11]	Conde-Frias M, Otero L, Restrepo J C, et al. Experimental analysis of infragravity waves in two eroded microtidal beaches[J]. Acta Oceanologica Sinica, 2017, 36(5): 31−43. doi: 10.1007/s13131-017-1054-7
[12]	Grinsted A, Moore J C, Jevrejeva S. Application of the cross wavelet transform and wavelet coherence to geophysical time series[J]. Nonlinear Processes in Geophysics, 2004, 11(5/6): 561−566. doi: 10.5194/npg-11-561-2004
[13]	Wang Gang, Nguyena V T, Zheng Jinhai, et al. Disintegration of linear edge waves[J]. China Ocean Engineering, 2013, 27(4): 557−562. doi: 10.1007/s13344-013-0047-3
[14]	Reniers A J H M, Battjes J A. A laboratory study of longshore currents over barred and non-barred beaches[J]. Coastal Engineering, 1997, 30(1): 1−21.
[15]	Tang Jun, Lü Yigang, Shen Yongming, et al. Numerical study on influences of breakwater layout on coastal waves, wave-induced currents, sediment transport and beach morphological evolution[J]. Ocean Engineering, 2017, 141: 375−387. doi: 10.1016/j.oceaneng.2017.06.042