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- Title
First Principles‐Based Approach for 3D Scour Processes Under Variable Jet Discharge.
- Authors
Di Nardi, J.; Palermo, M.; Bombardelli, F. A.; Pagliara, S.
- Abstract
Scour processes caused by plunging jets are particularly important in hydraulic engineering because of the connected risk of structural failure. Therefore, many investigations have been conducted on this topic, focusing on jet‐induced scour under constant flow discharge (i.e., steady case). Yet, to the best of the authors' knowledge, no studies have analyzed the scour mechanism under variable jet discharge (i.e., unsteady case) and clear‐water conditions. Following recent theoretical advancements on scour phenomena for steady cases based on the phenomenological theory of turbulence, we address in this study the general validity of such an approach for time‐dependent (i.e., unsteady) jet inflow conditions, in non‐cohesive soils. Results show that scour evolution is consistent with that obtained for steady jet flows. In particular, they confirm the existence of two distinct phases—developing and developed—and indicate that the transition time between the two phases does not depend on the jet inflow characteristics. Once again, this study confirms that the phenomenological theory of turbulence is a valid tool for all jet‐driven scour problems. Plain Language Summary: Localized scour processes occurring in correspondence with hydraulic structures in non‐cohesive soils are often associated with plunging jets. To limit the risk of failure of the structure, the evolution of the scour geometry should be carefully predicted. In the last decades, several empirical formulae have been proposed. Despite their successful application to specific structures, these tools appear to be reliable only under limited ranges of hydraulic conditions and geometric configurations. Therefore, the development of theoretical models is welcomed. To date, the theoretical analysis of scour evolution is essentially limited to steady flow conditions. Our analysis is herein focused on jet‐driven scour processes under variable discharge and clear‐water conditions. We conducted unprecedented tests allowing us to corroborate the applicability of our recent theoretical model based on the phenomenological theory of turbulence to the unsteady case. In so doing, we show that the scour mechanism exhibits similar features under both constant and variable flow discharges and provide insights into the effect of different inflow conditions. This study conclusively shows that the adopted approach represents a general and reliable tool to address such challenging phenomena. Key Points: The scour mechanism caused by a jet impinging on a granular bed was analyzed under variable jet discharge and clear‐water conditionScour evolution is consistent with that under steady flow conditionsThe phenomenological theory of turbulence was found to be a valid tool for all jet‐driven scour problems
- Subjects
STRUCTURAL failures; HYDRAULIC structures; JETS (Fluid dynamics); TURBULENCE; HYDRAULIC engineering; UNSTEADY flow; JET impingement
- Publication
Water Resources Research, 2022, Vol 58, Issue 11, p1
- ISSN
0043-1397
- Publication type
Article
- DOI
10.1029/2021WR030346