This paper makes an attempt to answer why the observed critical Shields stress for incipient sediment motion deviates from the Shields curve. The measured dataset collected from literature show that the critical Shields stress widely deviates from the Shields diagram's prediction. This paper has re-examined the possible mechanisms responsible for the validity of Shields' diagram and found that, among many factors, the vertical velocity in the sediment layer plays a leading role for the invalidity of Shield's prediction. A closer look of the positive/negative deviation reveals that they correspond to the up/downward vertical velocity, and the Shields diagram is valid only when flow is uniform. Therefore, this diagram needs to be modified to account for hydraulic environments when near bed vertical velocities are significant. A new theory for critical shear stress has been developed and a unified critical Shields stress for sediment transport has been established, which is valid to predict the critical shear stress of sediment in both uniform and nonuniform flows.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.