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Article

Velocity Structure of Density Currents Propagating over Rough Beds

1
Civil Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
2
Water and Environmental Engineering, School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia
3
Center for Coastal and Ocean Engineering (COEI), Research Institute of Sustainable Environment (RISE), Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia
*
Author to whom correspondence should be addressed.
Academic Editors: Jochen Aberle and Robert Bose
Water 2021, 13(11), 1460; https://doi.org/10.3390/w13111460
Received: 23 April 2021 / Revised: 16 May 2021 / Accepted: 20 May 2021 / Published: 23 May 2021
(This article belongs to the Special Issue Advances and Challenges in Hydropower)
In most practical cases, density-driven currents flow over surfaces that are not smooth; however, the effects of bottom roughness on these currents have not been fully understood yet. Hence, this study aims to examine the velocity structure of density currents while propagating over rough beds. To this end, alterations in the vertical velocity profiles within the body of these currents were investigated in the presence of different bottom roughness configurations. Initially, laboratory experiments were carried out for density currents flowing over a smooth surface to provide a baseline for comparison. Thereafter, seven bottom roughness configurations were tested, encompassing both dense and sparse bottom roughness. The bottom roughness consisted of repeated arrays of square cross-section beams covering the full channel width and perpendicular to the flow direction. The primary results indicate that the bottom roughness decelerated the currents and modified the shape of velocity profiles, particularly in the region close to the bed. Additionally, a critical spacing of the roughness elements was detected for which the currents demonstrated the lowest velocities. For the spacings above the critical value, increasing the distance between the roughness elements had little impact on controlling the velocity of these currents. Moreover, using dimensional analysis, equations were developed for estimating the mean velocities of the currents flowing over various configurations of the bottom roughness. The findings of this research could contribute towards better parameterization and improved knowledge of density currents flowing over rough beds. This can lead to a better prediction of the evolution of these currents in many practical cases as well as improved planning and design measures for the control of such currents. View Full-Text
Keywords: density current; velocity profile; acoustic doppler velocimeter; bottom roughness density current; velocity profile; acoustic doppler velocimeter; bottom roughness
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MDPI and ACS Style

Nasrollahpour, R.; Jamal, M.H.; Ismail, Z.; Ibrahim, Z.; Jumain, M.; Mohd Haniffah, M.R.; Ishak, D.S.M. Velocity Structure of Density Currents Propagating over Rough Beds. Water 2021, 13, 1460. https://doi.org/10.3390/w13111460

AMA Style

Nasrollahpour R, Jamal MH, Ismail Z, Ibrahim Z, Jumain M, Mohd Haniffah MR, Ishak DSM. Velocity Structure of Density Currents Propagating over Rough Beds. Water. 2021; 13(11):1460. https://doi.org/10.3390/w13111460

Chicago/Turabian Style

Nasrollahpour, Reza, Mohamad H. Jamal, Zulhilmi Ismail, Zulkiflee Ibrahim, Mazlin Jumain, Mohd R. Mohd Haniffah, and Daeng S.M. Ishak 2021. "Velocity Structure of Density Currents Propagating over Rough Beds" Water 13, no. 11: 1460. https://doi.org/10.3390/w13111460

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