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Does the critical shields stress for sediment transport depend on channel-bed slope?

Conference Paper


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Abstract


  • This paper investigates why the observed critical Shields stress for incipient sediment motion deviates

    from the Shields curve. This deviation is often described in the literature as due to measurement errors

    and non-uniformity of channel-bed slope or flows. On the contrary, this paper hypothesises the

    deviation as due to the presence of vertical velocity in open channel flows. We found that the

    existence of vertical velocity in non-uniform flows can lead to the deviation of critical shear stress from

    the standard Shield’s diagram that is valid only in uniform flows, and the channel bed slope could not

    contribute to the flow’s non-uniformity. The new hypothesis was successfully tested with the

    experimental data available in the literature. In addition, a new theory for critical shear stress has been

    developed, which shows that the decelerating flows promote the mobility of sediment, but accelerating

    flows constrain its mobility. A unified critical Shields stress for sediment transport has been

    established, that can predict the critical shear stress for sediment initial motion in both uniform and

    non-uniform flows.

Publication Date


  • 2012

Citation


  • Alfadhli, I., Yang, S. & Sivakumar, M. (2012). Does the critical shields stress for sediment transport depend on channel-bed slope?. 34th Hydrology and Water Resources Symposium-HWRS 2012 (pp. 117-128). Australia: Engineers Australia.

Scopus Eid


  • 2-s2.0-84925357475

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2492&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/1483

Start Page


  • 117

End Page


  • 128

Place Of Publication


  • Australia

Abstract


  • This paper investigates why the observed critical Shields stress for incipient sediment motion deviates

    from the Shields curve. This deviation is often described in the literature as due to measurement errors

    and non-uniformity of channel-bed slope or flows. On the contrary, this paper hypothesises the

    deviation as due to the presence of vertical velocity in open channel flows. We found that the

    existence of vertical velocity in non-uniform flows can lead to the deviation of critical shear stress from

    the standard Shield’s diagram that is valid only in uniform flows, and the channel bed slope could not

    contribute to the flow’s non-uniformity. The new hypothesis was successfully tested with the

    experimental data available in the literature. In addition, a new theory for critical shear stress has been

    developed, which shows that the decelerating flows promote the mobility of sediment, but accelerating

    flows constrain its mobility. A unified critical Shields stress for sediment transport has been

    established, that can predict the critical shear stress for sediment initial motion in both uniform and

    non-uniform flows.

Publication Date


  • 2012

Citation


  • Alfadhli, I., Yang, S. & Sivakumar, M. (2012). Does the critical shields stress for sediment transport depend on channel-bed slope?. 34th Hydrology and Water Resources Symposium-HWRS 2012 (pp. 117-128). Australia: Engineers Australia.

Scopus Eid


  • 2-s2.0-84925357475

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2492&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/1483

Start Page


  • 117

End Page


  • 128

Place Of Publication


  • Australia