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    • Keywords


      Ripple formation; turbulence; wave; Hilbert transform; wavelet transform.

    • Abstract


      The study reports an experimental investigation on the mechanism of the formation and development of isolated ripple zones over sand bed under unidirectional surface wave propagation. The ripple formation emerges due to the occurrence of vortices at the near-bed region under propagating wave fronts. A number of ripple patches are noticed after 100 cycles of the surface wave. To characterise these patches, Hilbert transform is used. These patches develop as a function of the number of wave cycles following Power law. Further, the rate of development of these patches increases with the increase of surface wave frequency as also reported in the literature. It is revealed that non-isolated turbulence singularity (random phase fractal signal) governs the erosion and deposition of sediment particles at the trough and crest of a progressive ripple front. The anti-phase behaviour of turbulence signal increases the wave excitation energy which may enhance the sediment erosion and transportation rate. However, it is hypothesized that the out-of-phase behaviour with moderate wave excitation energy contributes to the sediment deposition. Due to this, the frontal portion of the ripple does not attain a stable form and develops further.

    • Author Affiliations



      1. Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology (IIEST), Shibpur 711 103, India.
      2. Department of Mechanical Engineering, KPR Institute of Engineering and Technology, Arasur, Tamil Nadu 641 407, India.
      3. Department of Applied Mathematics with Oceanology and Computer Programming, Vidyasagar University, Midnapore 721 102, India.
    • Dates

  • Journal of Earth System Science | News

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      Posted on July 25, 2019

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