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Article

A Study on the Friction Factor and Reynolds Number Relationship for Flow in Smooth and Rough Channels

Department of Civil and Environmental Engineering, Pusan National University, Busandaehak-ro, 63beon-gil, Geumjeong-gu, Busan 46241, Korea
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Academic Editor: Mouldi Ben Meftah
Water 2021, 13(12), 1714; https://doi.org/10.3390/w13121714
Received: 1 June 2021 / Revised: 16 June 2021 / Accepted: 16 June 2021 / Published: 21 June 2021
The shear velocity and friction coefficient for representing the resistance of flow are key factors to determine the flow characteristics of the open-channel flow. Various studies have been conducted in the open-channel flow, but many controversies remain over the form of equation and estimation methods. This is because the equations developed based on theory have not fully interpreted the friction characteristics in an open-channel flow. In this paper, a friction coefficient equation is proposed by using the entropy concept. The proposed equation is determined under the rectangular, the trapezoid, the parabolic round-bottomed triangle, and the parabolic-bottomed triangle open-channel flow conditions. To evaluate the proposed equation, the estimated results are compared with measured data in both the smooth and rough flow conditions. The evaluation results showed that R (correlation coefficient) is found to be above 0.96 in most cases, and the discrepancy ratio analysis results are very close to zero. The advantage of the developed equation is that the energy slope terms are not included, because the determination of the exact value is the most difficult in the open-channel flow. The developed equation uses only the mean velocity and entropy M to estimate the friction loss coefficient, which can be used for maximizing the design efficiency. View Full-Text
Keywords: friction coefficient; open-channel flow; entropy; Reynolds number friction coefficient; open-channel flow; entropy; Reynolds number
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MDPI and ACS Style

Choo, Y.-M.; Kim, J.-G.; Park, S.-H. A Study on the Friction Factor and Reynolds Number Relationship for Flow in Smooth and Rough Channels. Water 2021, 13, 1714. https://doi.org/10.3390/w13121714

AMA Style

Choo Y-M, Kim J-G, Park S-H. A Study on the Friction Factor and Reynolds Number Relationship for Flow in Smooth and Rough Channels. Water. 2021; 13(12):1714. https://doi.org/10.3390/w13121714

Chicago/Turabian Style

Choo, Yeon-Moon, Jong-Gu Kim, and Sang-Ho Park. 2021. "A Study on the Friction Factor and Reynolds Number Relationship for Flow in Smooth and Rough Channels" Water 13, no. 12: 1714. https://doi.org/10.3390/w13121714

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