Computation of three-dimensional flow around square and circular piers

Tseng, Ming-Hseng; Yen, Chin-Lien; Song, Charles C. S.

doi:10.1002/1097-0363(20001015)34:3<207::aid-fld31>3.0.co;2-r

Cited by 87 publications

(39 citation statements)

References 15 publications

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“…Several LES computations have been performed in surface-mounted cubes at Re = 4.0 × 10 4 reporting bimodal pdfs of velocity [14,19,20] and a general agreement with the averaged turbulence intensities observed in experiments, but discrepancies still remain that have been attributed to the specifications of unsteady inflow boundary conditions and to the resolution of the approaching turbulent boundary-layer [14]. LES calculations of wall mounted vertical cylinders [31] only obtained averaged magnitudes of pressure and shear-stress of Dargahi's experiments [7], using a coarse grid of only 5.3 × 10 4 grid nodes.…”

Section: Introductionmentioning

confidence: 62%

Reynolds Number Effects on the Coherent Dynamics of the Turbulent Horseshoe Vortex System

Escauriaza

Sotiropoulos

2010

Flow Turbulence Combust

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The adverse pressure gradient induced by a surface-mounted obstacle in a turbulent boundary layer causes the approaching flow to separate and form a dynamically rich horseshoe vortex system (HSV) in the junction of the obstacle with the wall. The Reynolds number of the flow (Re) is one of the important parameters that control the rich coherent dynamics of the vortex, which are known to give rise to low-frequency, bimodal fluctuations of the velocity field (Devenport and Simpson, J Fluid Mech 210: 23-55, 1990; Paik et al., Phys Fluids 19:045107, 2007). We carry out detached eddy simulations (DES) of the flow past a circular cylinder mounted on a rectangular channel for Re = 2.0 × 10 4 and 3.9 × 10 4 (Dargahi, Exp Fluids 8: [1][2][3][4][5][6][7][8][9][10][11][12] 1989) in order to systematically investigate the effect of the Reynolds number on the HSV dynamics. The computed results are compared with each other and with previous experimental and computational results for a related junction flow at a much higher Reynolds number (Re = 1.15 × 10 5 ) (Devenport and Simpson, J Fluid Mech 210: 23-55, 1990; Paik et al., Phys Fluids 19:045107, 2007). The computed results reveal significant variations with Re in terms of the mean-flow quantities, turbulence statistics, and the coherent dynamics of the turbulent HSV. For Re = 2.0 × 10 4 the HSV system consists of a large number of necklace-type vortices that are shed periodically at higher frequencies than those observed in the Re = 3.9 × 10 4 case. For this latter case the number of large-scale vortical structures that comprise the instantaneous HSV system is reduced significantly and the flow dynamics becomes quasi-periodic. For both cases, we show that the instantaneous flowfields are dominated by eruptions of wall-generated vorticity associated with the growth of hairpin vortices that wrap around and disorganize the primary HSV 232 Flow Turbulence Combust (2011) 86:231-262 system. The intensity and frequency of these eruptions, however, appears to diminish rapidly with decreasing Re. In the high Re case the HSV system consists of a single, highly energetic, large-scale necklace vortex that is aperiodically disorganized by the growth of the hairpin mode. Regardless of the Re, we find pockets in the junction region within which the histograms of velocity fluctuations are bimodal as has also been observed in several previous experimental studies.

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Section: Introductionmentioning

confidence: 62%

Reynolds Number Effects on the Coherent Dynamics of the Turbulent Horseshoe Vortex System

Escauriaza

Sotiropoulos

2010

Flow Turbulence Combust

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“…C: A trailing vortex system develops from three-dimensional fl ow separation downstream of the obstacle and far-wake a fourth vortex system forms, resulting from the interaction of the trailing and wake vortex systems. Breusers et al, 1977;Breusers and Raudkivi, 1991;Hoffmans and Verheij, 1997;Olsen and Kjellesvig, 1998;Melville and Coleman, 2000;Tseng et al, 2000). Especially some fl ume experiments with submerged or free-surface obstacles are diffi cult to apply in the fi eld, as they are valid only for the limited range of conditions they are calibrated on (Johnson, 1995) and scale effects are frequently not regarded (Ettema et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of Pleistocene ice-dammed lake outburst floods in the Altai Mountains, Siberia

Herget¹

2005

Reconstruction of Pleistocene Ice-Dammed Lake Outburst Floods in the Altai Mountains, Siberia

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In the Siberian Altai Mountains, where the sources of the River Ob are located, ice-dammed lake outburst fl oods, so-called jökulhlaups, occurred in Pleistocene times. Valley glaciers extended within the upper Chuja River catchment and dammed the river upstream of the village of Aktash, which generated ice-dammed lakes in the intramountainous Kuray and Chuja Basins. Indicated by shorelines and ice-rafted boulder deposits, the maximum lake level reached an altitude of 2100 m above sea level, which reveals a maximum lake volume of 607 km 3 . The failure of the ice dam caused outburst fl oods, which left traces by giant bars, fl uvial gravel dunes, and boulder deposits. Run-up sediments deposited in front of local obstructions along the valley slopes indicate a maximum depth of fl ow of 400 m above the valley bottom. Like the giant bars, they consist of characteristic relatively fi ne suspension gravels. Occasionally, secondary lakes are formed in tributary valleys that were blocked by giant bar deposits. The alternation of lacustrine deposits and suspension gravels in the tributary Injushka valley near Inja village give evidence for at least three large outburst fl oods. Age estimations by a variety of dating methods, such as luminescence methods, exposure dating, and accelerator mass spectrometry radiocarbon applied on different fl ood features and lake sediments, indicate that the outburst fl oods occurred between 40 ka and 13 ka. This estimation should be taken as preliminary, as problems occurred with the different dating techniques, resulting in partly contradictory results. This study focuses on the paleohydraulic reconstruction of the fl ood rather than describing fl ood-related features in detail. Seven different approaches are applied to estimate the discharge of the fl oods. Several new methods are developed within the study, partly based on previous approaches carefully considering the hydraulic background. Data for paleohydraulic estimations are obtained during repeated fi eld trips by observations, surveys, and sedimentological investigations in Chuja and Katun valleys. Peak discharge is estimated by the elevation of the surfaces of the giant bars indicating the depth of fl ow and additionally by the run-up sediments, which reveal information about the velocity head of the fl ood fl ow along the valleys. A value of 10 × 10 6 m 3 /s is estimated for peak discharge, which is considerably less than previous estimations derived. Dimensions of gravel dunes and obstacle marks obtain information of fl ow conditions during the decreasing fl ood. The application of regression formulae between drained lake volume and peak discharge, an established method to estimate discharges of jökulhlaups, and estimation of fl ow velocity considering fl ow *herget @giub.uni-bonn.de on May 27, 2015 specialpapers.gsapubs.org Downloaded from 2 J. Herget competence indicated by transported boulders yield problems as the magnitude of the outburst fl oods and the size of the boulders are beyond the level of experience.Based on the...

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“…The other approach is to rely on computational methods. Recent developments in computational fluid dynamics allow numerical simulations of local scour around a bridge pier (Olsen and Melaaen, 1993;Richardson and Panchang, 1998;Wang and Jia, 2000;Li and Lin, 2000;Tseng et al, 2000). For this, one has to consider a movable boundary with a sophisticated turbulence closure.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Local Scour Around Bridge Piers Using Artificial Neural Networks

Choi¹,

Cheong

2006

J Am Water Resources Assoc

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This paper describes a method for predicting local scour around bridge piers using an artificial neural network (ANN). Methods for selecting input variables, calibrations of network control parameters, learning process, and verifications are also discussed. The ANN model trained by laboratory data is applied to both laboratory and field measurements. The results illustrate that the ANN model can be used to predict local scour in the laboratories and in the field better than other empirical relationships that are currently in use. A parameter study is also carried out to investigate the importance of each input variable as reflected in data.

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Computation of three-dimensional flow around square and circular piers

Cited by 87 publications

References 15 publications

Reynolds Number Effects on the Coherent Dynamics of the Turbulent Horseshoe Vortex System

Reynolds Number Effects on the Coherent Dynamics of the Turbulent Horseshoe Vortex System

Reconstruction of Pleistocene ice-dammed lake outburst floods in the Altai Mountains, Siberia

Prediction of Local Scour Around Bridge Piers Using Artificial Neural Networks

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