Journal article
Detached Eddy Simulation Investigation of Turbulence at a Circular Pier with Scour Hole
Journal of Hydraulic Engineering, Vol.135(11), pp.888-901
11/2009
DOI: 10.1061/(ASCE)HY.1943-7900.0000101
Abstract
This paper uses results from detached eddy simulation to reveal the dynamics of large-scale coherent eddies in the flow around a circular pier with an equilibrium scour hole. This is important for the sediment transport because the local scour process is controlled to a large extent by the large-scale coherent structures present in the near-bed region. The present paper investigates the dynamics of these coherent structures, their interactions and their role in entraining sediment in the later stages of the scour process when the horseshoe vortex system is stabilized by the presence of a large scour hole. The pier Reynolds number was
2.06×
105
, outside the range of well-resolved large-eddy simulation (LES). Additionally, scale effects are investigated based on comparison with LES results obtained at a much lower Reynolds number of 16,000 in a previous investigation. The paper provides a detailed study of the dynamics of the main necklace vortices of the horseshoe vortex system, including an investigation of the bimodal oscillations, their effect on the amplification of the turbulence within the scour hole and the interactions of the necklace vortices with the downflow. Several mechanisms for the growth of the downstream part of the scour hole in the later stages of the scour process are discussed. Similar to the low-Reynolds-number simulation, and consistent with experimental observations, the presence of strong upwelling motions near the symmetry plane resulted in the suppression of the large-scale vortex shedding in the wake. The fact that the nondimensional values of the turbulent kinetic energy and pressure RMS fluctuations in the higher Reynolds number simulation were consistently lower inside the regions of high turbulence amplification associated with the main necklace vortex, the separated shear layers and the near-wake shows that changes in the flow and turbulence due to the Reynolds number and scour hole geometry can be quantitatively significant over Reynolds numbers between
104
and
105
.
Details
- Title: Subtitle
- Detached Eddy Simulation Investigation of Turbulence at a Circular Pier with Scour Hole
- Creators
- G Kirkil - Lawrence Livermore National Laboratory , Atmospheric, Earth, and Energy Div., , P.O. Box 808, L-103, Livermore, CA 94551; formerly, Graduate Research Assistant, Dept. of Civil and Environmental Engineering, IIHR-Hydroscience and Engineering, Stanley Hydraulics Laboratory, The Univ. of Iowa, Iowa City, IA 52242. E-mailG Constantinescu - The Univ. of Iowa , Civil and Environmental Engineering, IIHR-Hydroscience and Engineering, Stanley Hydraulics Laboratory, , Iowa City, IA 52242 (corresponding author). E-mailR Ettema - The Univ. of Wyoming , College of Engineering and Applied Science, , Laramie, WY 82071. E-mail
- Resource Type
- Journal article
- Publication Details
- Journal of Hydraulic Engineering, Vol.135(11), pp.888-901
- DOI
- 10.1061/(ASCE)HY.1943-7900.0000101
- ISSN
- 0733-9429
- eISSN
- 1943-7900
- Publisher
- American Society of Civil Engineers
- Language
- English
- Date published
- 11/2009
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9983991955802771
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