Frontiers of Structural and Civil Engineering
>> 2020,
Volume 14,
Issue 6
doi:
10.1007/s11709-020-0648-x
RESEARCH ARTICLE
Alluvial channel hydrodynamics around tandem piers with downward seepage
. Department of Civil Engineering, Maulana Azad National Institute of Technology Bhopal, Bhopal, Madhya Pradesh 462003, India.. Department of Harbor, School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430072, China.. Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India
Received: 2020-09-30
Accepted: 2020-12-07
Available online: 2020-12-07
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Abstract
In this paper, we report the turbulent flow structures and the scour geometry around two piers with different diameters. An experiment was conducted on a non-uniform sand bed with two types of tandem arrangements, namely, pier (T1) with a 75 mm front and 90 mm rear, and pier (T2) with a 90 mm front and 75 mm rear, with and without-seepage flows, respectively. A strong wake region was observed behind the piers, but the vortex strength diminished with downward seepage. Streamwise velocity was found to be maximum near the bed downstream of the piers and at the edge of the scour hole upstream of the piers. Quadrant analysis was used to recognize the susceptible region for sediment entrainment and deposition. Upstream of the piers near the bed, the moments, turbulent kinetic energy (TKE), and TKE fluxes were found to decrease with downward seepage, in contrast to those in a plane mobile bed without piers. The reduction percentages of scour depth at the rear pier compared with the front one were approximately 40% for T1 and 60% for T2. Downward seepage also resulted in restrained growth of scouring with time.
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