Phase-lag effects in oscillatory sheet flow

C. Marjolein Dohmen-Janssen, Gizella van der Hout, Jan S. Ribberink

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    Abstract

    It is often assumed that in sheet flow conditions the transport rate in oscillatory flow behaves quasi-steady, i.e. showing a direct relation with the instantaneous flow velocity (e.g. Ribberink et ah, 1994). In this paper it will be shown that this assumption is not always valid. Therefore a new semi-unsteady sand transport model is developed which takes into account phase-lag effects of the sediment on the net transport rate. In order to verify this new semi-unsteady model and two existing quasi-steady models, new experiments were performed in the Large Oscillating Water Tunnel (LOWT) of WL \ DELFT HYDRAULICS. Together with earlier experiments these measurements form a data set of net sand transport rates of uniform sand for three different grain sizes (D50 = 0.13; 0.21 and 0.32 mm) in combined wave-current sheetflow conditions. The verification shows that phase-lag effects become important for a combination of fine sand, large flow velocities and small wave periods. Under these conditions the quasi-steady models cannot predict the behaviour of the net transport rates correctly and the predictions of the new semi-unsteady model show much better agreement.
    Original languageEnglish
    Title of host publicationCoastal Engineering 1998
    Subtitle of host publicationConference proceedings, June 22-26, 1998, Copenhagen, Denmark
    EditorsBilly L. Edge
    Place of PublicationReston, VA
    PublisherAmerican Society of Civil Engineers
    Pages2449-2462
    Number of pages14
    Volume3
    ISBN (Print)0-7844-0411-9
    Publication statusPublished - 1 Jan 1999
    Event26th International Conference on Coastal Engineering, ICCE 1998 - Copenhagen, Denmark
    Duration: 22 Jun 199827 Jun 1998
    Conference number: 26

    Publication series

    NameCoastal engineering proceedings
    PublisherASCE
    Volume26
    ISSN (Print)2156-1028

    Conference

    Conference26th International Conference on Coastal Engineering, ICCE 1998
    Abbreviated titleICCE
    CountryDenmark
    CityCopenhagen
    Period22/06/9827/06/98

    Keywords

    • Sheetflow
    • Oscillatory flow
    • Phase lag

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