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Open AccessArticle

Numerical Study of the Velocity Decay of Offset Jet in a Narrow and Deep Pool

State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China
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Water 2019, 11(1), 59; https://doi.org/10.3390/w11010059
Received: 29 November 2018 / Revised: 24 December 2018 / Accepted: 25 December 2018 / Published: 31 December 2018
(This article belongs to the Special Issue Advances in Hydraulics and Hydroinformatics)
The present study examines the configuration of an offset jet issuing into a narrow and deep pool. The standard k-ε model with volume-of-fluid (VOF) method was used to simulate the offset jet for three exit offset ratios (OR = 1, 2 and 3), three expansion ratios (ER = 3, 4 and 4.8), and different jet exits (circular and rectangular). The results clearly show significant effects of the circumference of jet exits (Lexit) in the early region of flow development, and a fitted formula is presented to estimate the length of the potential core zone (LPC). Analysis of the flow field for OR = 1 showed that the decay of cross-sectional streamwise maximum mean velocity (Um) in the transition zone could be fitted by power law with the decay rate n decreased from 1.768 to 1.197 as the ER increased, while the decay of Um for OR = 2 or 3 was observed accurately estimated by linear fit. Analysis of the flow field of circular offset jet showed that Um for OR = 2 decayed fastest due to the fact that the main flow could be spread evenly in floor-normal direction. For circular jets, the offset ratio and expansion ratio do not affect the spread of streamwise velocity in the early region of flow development. It was also observed that the absence of sudden expansion of offset jet is analogous to that of a plane offset jet, and the flow pattern is different. View Full-Text
Keywords: offset jet; potential core; decay rate; k-ε model offset jet; potential core; decay rate; k-ε model
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MDPI and ACS Style

Li, X.; Zhou, M.; Zhang, J.; Xu, W. Numerical Study of the Velocity Decay of Offset Jet in a Narrow and Deep Pool. Water 2019, 11, 59.

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