https://orcid.org/0000-0002-2081-2263
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ABSTRACT
The roughness Froude number is a relatively new dimensionless parameter that began appearing in the hydraulic engineering literature in the late 1970s, first for the analysis of aeration inception in smooth chutes, and then later in connection with stepped chutes. This article reviews its foundations, historical development, alternative forms, present-day applications, and physical significance, which has received little attention previously. In addition to its empirically demonstrated connection to aeration inception, this paper shows that one form of a roughness Froude number has a strong relation to the transition between nappe and skimming flow regimes of stepped chutes, while another combines the dimensionless flow friction factor and the relative submergence of roughness elements.
Acknowledgements
The author greatly appreciates the contributions of the anonymous reviewers and associate editor who made insightful comments that led to significant improvement of the paper, especially the suggested alternate physical interpretation of F* as a combination of the friction factor and relative submergence of roughness elements.
Disclosure statement
No potential conflict of interest was reported by the author.