Effect of spur dike length on the horseshoe vortex system and the bed shear stress distribution

Turbulent flow structures forming around isolated spur dikes in a horizontal channel are investigated in this study. In the analysis detached eddy simulation is used under fully turbulent incoming flow conditions at a channel Reynolds number of 45,000. Changes in the structure of the horseshoe vortex system, bed shear stress and pressure standard deviation on the bed are investigated for three different spur dike lengths. In all of the cases the main horseshoe vortex undergoes bimodal oscillations, which leads to an amplification in the turbulence quantities such as turbulent kinetic energy and pressure fluctuations along its axis. The main horseshoe vortex disappears over a much shorter distance in the flow direction for the short spur dike than those of medium and long spurs. Large bed shear stress values and pressure standard deviation values observed around the tip of the spur dike, beneath the upstream part of the main horseshoe vortex and beneath the separated shear layers increase with the increasing length of the spur dike. Different from the long and medium spur dike, in the short spur dike case, it is shown that the secondary horseshoe vortex is as coherent as the main horseshoe vortex and it contains bimodal oscillations together with the main horseshoe vortex.


Coherent structures around isolated spur dikes at various approach flow angles
Köken, Mete (2011-01-01)
The turbulent flow structures around an isolated spur dike located at three different approach flow angles are investigated. Detached eddy simulation is used at a channel Reynolds number of 45,000. Experimental velocity measurements were also conducted using acoustic Doppler velocimetry for validating the simulations. It is found that the size and orientation of the horseshoe vortex system change considerably with the approach flow angle. The main necklace vortex is largest in size and most coherent for 90 ...
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Detached Eddy Simulation (DES) is used to investigate the changes in the horseshoe vortex system and the bed shear stress distribution forming around the base of spill-through bridge abutments located at two sides of the channel for two different contraction ratios. DES is conducted at a channel Reynolds number of 45,000, and the incoming flow was fully turbulent that contains resolved turbulence fluctuations. Simulations are conducted at flat bed conditions representing the initiation of the scour process....
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Göğüş, Mustafa; Atalay, Ahmet E. (2013-10-01)
In this study, the effect of the downstream expansion region of a flow measurement flume of rectangular compound cross section on some of the flow properties; such as the discharge coefficient, C-d, the approach velocity coefficient, C and the modular limit, ML were investigated. For this reason, extensive laboratory tests were conducted with nine models of different downstream transitions. The aforementioned hydraulic quantities were then related with the relevant parameters to obtain sets of curves from w...
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The primary objective of this study is to investigate experimentally local scours around bridge pier groups at various inclination angles of piers and also to develop empirical local scour depth equations. In the study, two bridge pier groups are used. In each pier group, the most upstream and downstream piers are placed in an inclined manner at 10 degrees and 15 degrees. The vertical case was also employed for comparison purposes. Seventy-two experiments each lasting 6 h are conducted under uniform-flow an...
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Citation Formats
M. Köken and M. Göğüş, “Effect of spur dike length on the horseshoe vortex system and the bed shear stress distribution,” JOURNAL OF HYDRAULIC RESEARCH, pp. 196–206, 2015, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/31888.