American Society of Civil Engineers


Reattached Turbulent Submerged Offset Jets on Rough Beds with Shallow Tailwater


by Faruk Bhuiyan, (Visiting Professor, Dept. of Civil and Environmental Engineering, Univ. of Alberta, Edmonton, AB, Canada T6G 2W2; and Professor, Dept. of Water Resources Engineering, Bangladesh Univ. of Engineering and Technology, Dhaka 1000, Bangladesh. E-mail: abmfbhuiyan@wre.buet.ac.bd), Alireza Habibzadeh, (Graduate student, Dept. of Civil and Environmental Engineering, Univ. of Alberta, Edmonton, AB, Canada T6G 2W2. E-mail: habibzad@ualberta.ca), N. Rajaratnam, (corresponding author), F.ASCE, (Professor Emeritus, Dept. of Civil and Environmental Engineering, Univ. of Alberta, Edmonton, AB, Canada T6G 2W2. E-mail: nrajaratnam@ualberta.ca), and David Z. Zhu, M.ASCE, (Professor, Dept. of Civil and Environmental Engineering, Univ. of Alberta, Edmonton, AB, Canada T6G 2W2. E-mail: david.zhu@ualberta.ca)

Journal of Hydraulic Engineering, Vol. 137, No. 12, December 2011, pp. 1636-1648, (doi:  http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0000462)

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Document type: Journal Paper
Abstract: This study investigates the characteristics of reattached plane turbulent offset jets in channels with rough beds and shallow tailwater depths. The flow consists of a deflecting free jet caused by the Coanda effect and the evolving wall jet past reattachment. In limited tailwater conditions, the jet flow is affected by the relative tailwater depth or the submergence parameter, which is defined with respect to the maximum B-jump at a negative step. The results show that for an offset height larger than the jet thickness, the forward-flow momentum, local maximum velocity, and wall shear stress decrease faster in the longitudinal direction in the offset jet than in plane turbulent wall jets. The influence of roughness on reattached offset jets appears to be less than that in submerged wall jets on a similar rough bed. The presented results and the comparative analysis with respect to wall jets in hydraulic jumps are significant for controlling and implementing similar flows on rough beds with variable downstream water levels.


ASCE Subject Headings:
Tail water
Turbulence
Submerging
Jets (fluid)
Shallow water

Author Keywords:
Offset jet
Rough bed
Tailwater effect
Hydraulic jump
Negative step
Flow momentum