Navier‐Stokes computations of horseshoe vortex flows

Deng, Ganbo; Piquet, J.

doi:10.1002/fld.1650150108

Cited by 17 publications

(5 citation statements)

References 16 publications

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“…Using a three-dimensional incompressible N-S code, Kwak et al (1986) computed the laminar steady junction flow. Deng & Piquet (1992) studied the three-dimensional turbulent flow about an airfoil/flat-plate junction, where the main features of the horseshoe vortex are captured by the study. An iterative fully decoupled technique was applied to the Reynolds-averaged N-S equations in this study.…”

Section: Introductionmentioning

confidence: 99%

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Numerical and experimental investigation of flow and scour around a circular pile

et al. 2005

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The flow around a vertical circular pile exposed to a steady current is studied numerically and experimentally. The numerical model is a three-dimensional model. The model validation was achieved against new experimental data (which include two-component laser-Doppler anemometry (LDA) flow measurements and the hot-film bed shear stress measurements, and reported in the present paper) and the data of others, and a $k$–$\omega $ turbulence model was used for closure. The model does not have a free-surface facility and therefore is applicable only to cases where the Froude number is small ($\hbox{\it Fr}\,{<}\,O(0.2)$). The flow model was used to study the horseshoe vortex and lee-wake vortex flow processes around the pile. The influence on the horseshoe vortex of three parameters, namely the boundary-layer thickness, the Reynolds number and the bed roughness, was investigated. In the latter investigation, the steady solution of the model was chosen. A study of the influence of the unsteady solution on the previously mentioned flow processes was also carried out. The ranges of the parameters covered in the numerical simulations are: The boundary-layer-thickness-to-pile-diameter ratio is varied from 2$\,{\times}\, 10^{-2}$ to 10$^{2}$, the pile Reynolds number from 10$^{2}$ to $2\,{\times}\, 10^{6},$ and the pile diameter-to-roughness ratio from 2 to about 10$^{3}.$ The amplification of the bed shear stress around the pile (including the areas under the horseshoe vortex and the lee-wake region) was obtained for various values of the previously mentioned parameters. The steady-state flow model was coupled with a morphologic model to calculate scour around a vertical circular pile exposed to a steady current in the case of non-cohesive sediment. The morphologic model includes (i) a two-dimensional bed load sediment-transport description, and (ii) a description of surface-layer sand slides for bed slopes exceeding the angle of repose. The results show that the present numerical simulation captures all the main features of the scour process. The equilibrium scour depth obtained from the simulation agrees well with the experiments for the upstream scour hole. Some discrepancy (up to 30%) was observed, however, for the downstream scour hole. The calculations show that the amplification of the bed shear stress around the pile in the equilibrium state of the scour process is reduced considerably with respect to that experienced at the initial stage where the bed is plane.

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Section: Introductionmentioning

confidence: 99%

“…An iterative fully decoupled technique was applied to the Reynolds-averaged N-S equations in this study. A comprehensive review of the work up to the early 1990s was given by Deng & Piquet (1992).…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental investigation of flow and scour around a circular pile

et al. 2005

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“…This is why the vortex core is located at a higher position in the present study. The horseshoe vortices were symmetrical around the center lines of the obstacles in the Science and Technology Vol.3, No.6, 2008 previous works (7) - (9) . However, the present vortices are asymmetrical because of the swirling flow at the inlet boundary.…”

Section: Effect Of Piermentioning

confidence: 68%

“…The distances from the bottom plane to the vortex core ranged from y/t ∼ 0.04 − 0.05 in his experiments on laminar flow. Here, the distances were normalized by the diameter of the obstacle, t. Deng & Piquet (9) carried out RANS simulations on the turbulent flow around a 2-dimensional wing perpendicular to a flat plane. They surmised that the height at which the center of the horseshoe vortex appeared was around y/t ∼ 0.034, where t was the maximum thickness of the wing.…”

Section: Effect Of Piermentioning

confidence: 99%

Numerical Investigations into Horseshoe Vortices in Draft Tubes of Bulb Turbines

Shingai

Araki

Tani

2008

JFST

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The series of flows around the piers in draft tubes of bulb turbines were investigated. The flow fields were assumed to be steady incompressible turbulent flows. The primary factor responsible for total pressure loss in draft tubes was investigated based on the data obtained. Well-known horseshoe-shaped vortices were observed at the leading edges of piers as a result of simulations. These vortex structures were found to greatly contribute to total pressure loss in the present cases. Simulations on several variously shaped draft tubes were carried out and these suggested slight modifications to draft tubes would effectively curtail total pressure loss around a pier.

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“…The fluctuation of turbulent flows on a wide range of time and length scales makes their numerical computation difficult and requires a specific way of modelling this turbulence. The Reynolds-Averaged Navier-Stokes (RANS) equations are such model equations, and were used in the first application of Computational Fluid Dynamic (CFD) tools by Deng and Piquet [17], to study the three-dimensional turbulent flow around an airfoil. The use of an iterative, fully decoupled technique to compute the RANS equations proved to be an attractive approach to capture the main features of horseshoe vortices, although they lacked some accuracy in modelling the scouring process.…”

Section: Introductionmentioning

confidence: 99%

Scour Development Around an Oblong Bridge Pier: A Numerical and Experimental Study

Bento

Pêgo

Viseu

et al. 2023

Water

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The complex flow structure around bridge piers is challenging for both experimental and numerical studies. Therefore, investigating the capabilities of Computational Fluid Dynamics (CFD) tools in resolving the flow structure and the mechanism of sediment entrainment into and out of the scour hole remains a challenging task. In this study, the scour depth around an oblong bridge pier and the bed shear stress distributions in time and space were numerically investigated using the Computational Fluid Dynamics (CFD) tool Sediment Simulation In Intakes with Multiblock option (SSIIM). Clear water scour conditions and sand of known granulometric composition were considered in accordance with the experimental study carried out. Laboratory data and the results of a scour characterization around a 0.11 m wide oblong bridge pier were considered to calibrate and validate the numerical model. The averaged form of the Navier–Stokes equations was considered to simulate the turbulent flow fields in anticipation of long time scales. The results show that calibrated numerical models can reproduce measured scour depths in the laboratory environment with considerable accuracy, with an average relative error of less than 3%, especially around oblong bridge piers.

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Navier‐Stokes computations of horseshoe vortex flows

Cited by 17 publications

References 16 publications

Numerical and experimental investigation of flow and scour around a circular pile

Numerical and experimental investigation of flow and scour around a circular pile

Numerical Investigations into Horseshoe Vortices in Draft Tubes of Bulb Turbines

Scour Development Around an Oblong Bridge Pier: A Numerical and Experimental Study

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