Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Influence of boulder concentration on turbulence and sediment transport in open-channel flow over submerged boulders

Fang, H. W., Liu, Y. and Stoesser, Thorsten 2017. Influence of boulder concentration on turbulence and sediment transport in open-channel flow over submerged boulders. Journal of Geophysical Research. Earth Surface 122 (12) , pp. 2392-2410. 10.1002/2017JF004221

Full text not available from this repository.

Abstract

In this paper the effects of boulder concentration on hydrodynamics and local and reach-averaged sediment transport properties with a flow over submerged boulder arrays are investigated. Four numerical simulations are performed in which the boulders' streamwise spacings are varied. Statistics of near-bed velocity, Reynolds shear stresses, and turbulent events are collected and used to predict bed load transport rates. The results demonstrate that the presence of boulders at various interboulder spacings altered the flow field in their vicinity causing (1) flow deceleration, wake formation, and vortex shedding; (2) enhanced outward and inward interaction turbulence events downstream of the boulders; and (3) a redistribution of the local bed shear stress around the boulder consisting of pockets of high and low bed shear stresses. The spatial variety of the predicted bed load transport rate qs based on local bed shear stress is visualized and is shown to depend greatly on the boulder concentration. Quantitative bed load transport calculations demonstrate that the reach-averaged bed load transport rate may be overestimated by up to 25 times when including the form-drag-generated shear stress of the immobile boulders in the chosen bed load formula. Further, the reach-averaged bed load transport rate may be underestimated by 11% if the local variability of the bed shear stress is not accounted for. Finally, it is shown that for the small-spaced boulder array, the bed load transport rates should no longer be predicted using a normal distribution with standard deviation of the shear stress distribution σ.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Publisher: John Wiley and Sons Inc.
ISSN: 2169-9003
Date of Acceptance: 6 November 2017
Last Modified: 08 May 2019 02:37
URI: http://orca.cf.ac.uk/id/eprint/107890

Citation Data

Cited 2 times in Google Scholar. View in Google Scholar

Cited 2 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item Edit Item