Coherent structures at different contraction ratios caused by two spill-through abutments

Date

2017-8-23

Author

Köken, Mete

Metadata

Show full item record

Item Usage Stats

198
views

0
downloads

Detached eddy simulation (DES) at a channel Reynolds number of 45,000 is used to investigate the coherent structures forming around spill-through abutments located at opposite sides of a rectangular channel which contract the flow section. Changes in the coherent structures are investigated for two contraction ratios at two different scour stages. It is observed that at the small contraction ratio the coherent structures forming around the abutments are similar to the ones observed for isolated abutments. However, at the larger contraction ratio there are important changes in these structures. At the beginning of the scour process two counter rotating contraction vortices form close to the bed at the centre of the channel, oriented in the streamwise direction. At this initial scour stage, the upstream part of the main horseshoe vortex is incoherent. On the other hand, at a later stage of scour with the development of the scour hole contraction vortices disappear and the main horseshoe vortex regains its original shape.

Subject Keywords

Channel contraction, Coherent structures, Detached eddy simulation, River training structures, Turbulence simulation and modelling

URI

https://hdl.handle.net/11511/28260

Journal

Journal of Hydraulic Research

DOI

https://doi.org/10.1080/00221686.2017.1354930

Collections

Department of Civil Engineering, Article

Suggestions

OpenMETU
Core

Coherent structures in a sharply curved bend with and without a spur dike. Köken, Mete; Budak, Ezgi (null; 2017-08-18) : Results of three-dimensional (3D) Detached Eddy Simulation (DES) are used to investigate the changes in flow and large-scale coherent structures within a high-curvature open channel, with and without an isolated spur dike located on the outer bank of the
Numerical investigation of coherent structures forming around bridge piers sitting on an inclined surface Hesap, Emre; Köken, Mete; Department of Civil Engineering (2021-11) Coherent structures forming around the piers play an important role in the formation of scour hole. Detached Eddy Simulation is used in this study to investigate the three-dimensional coherent structures forming around bridge piers which sit on an inclined surface. Initiation of the scour process at flat bed conditions is investigated within the current study. Two cases are investigated one with the lower Reynolds number case which is typical for flume experiments whereas the larger Reynolds number case re...
Flow structure and large scale turbulence in an open channel bend of strong curvature with flat and deformed bed Constantinescu, G.; Köken, Mete (2014-09-05) Results of Three-Dimensional (3D) Detached Eddy Simulation (DES) are used to discuss changes in flow structure and large-scale turbulence structures in a high-curvature open channel between conditions present at the start (flat bed) and at the end (equilibrium deformed bed) of the erosion-deposition process. The flow in a 193 degrees bend is simulated, for which the ratio between the bend curvature and the channel width is close to 1.3. For these geometrical parameters, the cross-stream secondary flow and a...
Flow structure inside and around a rectangular array of rigid emerged cylinders located at the sidewall of an open channel Köken, Mete (Cambridge University Press (CUP), 2021-01-01) Flow structure inside and around a rectangular array of emerged cylinders located adjacent to the sidewall of an open channel is investigated using eddy-resolving numerical simulations. This configuration is particularly relevant for understanding how patches of aquatic vegetation developing near a river's banks affect flow and transport. The array of width W = 1.6D and length L = 33D-35D (D is the flow depth) contains rigid cylinders. Simulations with incoming, fully developed turbulent flow (channel Reyno...
An investigation of the dynamics of coherent structures in a turbulent channel flow with a vertical sidewall obstruction Köken, Mete (2009-08-01) The physics of the flow around a vertical-wall obstruction attached to one of the sidewalls of a straight channel is numerically investigated using detached eddy simulation (DES) at a high channel Reynolds number, Re=5 x 10(5) (case HR). In particular, the study investigates the role played by the large-scale coherent structures in the sediment entrainment processes at the bed for conditions close to the initiation of scour (flat bed) in a loose-bed channel. Scale effects are investigated by comparing the r...

Citation Formats

M. Köken, “Coherent structures at different contraction ratios caused by two spill-through abutments,” Journal of Hydraulic Research, pp. 324–332, 2017, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/28260.