Turbulence characteristics in wall-wake flows downstream of wall-mounted and near-wall horizontal cylinders

Dey, Subhasish; Lodh, Rajashree; Sarkar, Sankar

doi:10.1007/s10652-018-9573-0

Cited by 16 publications

(5 citation statements)

References 29 publications

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“…The locations of the peak in the RSSs profiles are corresponding to the locations of the points of inflection (d 2 u/dz 2 = 0) in the velocity distributions. The results obtained in this study are similar to those of Dey et al (2018) and Devi et al (2021a). The magnitudes of the peaks increase with the increase in the streamwise distance downstream of the cylinder up to the flow reattachment point.…”

Section: Reynolds Stressessupporting

confidence: 85%

“…3b). This location is similar to the location of the point of inflection by Dey et al (2018), Devi et al (2021a), Devi et al (2022) for a wall-mounted horizontal cylinder and Nepf and Ghisalberti (2008) for a dense canopy of vegetation. On inner scaling, the streamwise velocity distributions are not showing any effects of the Reynolds numbers.…”

Section: Mean Velocity Fieldsupporting

confidence: 57%

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Wake flow field of a wall-mounted pipe with spoiler on a rough channel bed

et al. 2023

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This research work focuses on the wake flow region of a cylinder with a spoiler on a rough bed under steady flow conditions. The acoustic Doppler velocimetry was used for the measurement of three-dimensional velocity data for two Reynolds numbers in a fully developed turbulent flow around the cylinder with a spoiler. The mean flow velocities, second-order turbulence structures, and conditional statistics were investigated in the wake region of the spoilered cylinder. The flow was separated from the spoiler with the formation of two shear layers between free surface flow and recirculating flow. It is observed that the flow is reattaching to the bed at 11D irrespective of the Reynolds number. Downstream of the cylinder, the mean velocity distributions are asymmetric due to the wall–wake effect, and the point of inflection is observed for each velocity profile at z = 0.40ẟ. The turbulence intensities, Reynolds stresses, and TKE are highly enhanced in the wake region of the cylinder as compared to their respective upstream values for both runs. The turbulence intensities, Reynolds normal stresses, Reynolds shear stresses, and turbulent kinetic energy are attaining peaks at z = 0.4 ẟ for all the streamwise locations, and the peaks are found to be highest at x = 10D. The quadrant analysis results indicate that the sweeps are dominating bursting events in the inner and intermediate layers, while ejections are dominating in the outer layer of the wake region. As the hole size, H increases ejections stress fraction rises as compared to that of the sweeps in the wake region for z = 0.2–0.7 h.

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Section: Reynolds Stressessupporting

confidence: 85%

Section: Mean Velocity Fieldsupporting

confidence: 57%

Wake flow field of a wall-mounted pipe with spoiler on a rough channel bed

et al. 2023

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“…the airflow around solar panels, flow around vehicles and the cooling of electronic components. Many investigations have been carried out with circular and square cylinders as a bluff body to examine the influence of the gap on the wake characteristics [1][2][3][4][5]. all these studies agree that the gap alters the wake characteristics if it is introduced in the wake flow.…”

Section: Introductionmentioning

confidence: 91%

Effect of gap on the flow characteristics in the wake of a bluff body near a wall

Nasif¹,

Balachandar²,

Barron³

2019

Int. J. CMEM

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a numerical investigation is carried out to evaluate the influence of the gap between the bluff body and the bed on the wake characteristics generated in shallow flows. a sharp-edge bluff body with a fixed gap from the bed is employed in the study, and the results are compared with the no gap case. a sharp-edged bluff body was chosen to minimize the effect of reynolds number and ensure fixed flow separation points. The transient three-dimensional Navier-Stokes equations are numerically solved using a finite volume approach with the detached eddy simulation turbulence model. The flow field in this study involves two different fluids, i.e. water and the air above it. The volume of fluid method is used for tracking the free surface separating the water and air. The fluid structures that are generated in the wake are identified using the λ 2 -criterion. The results reveal that the gap flow will develop a new structure near the bed, which enhances the upwash flow immediately after the submerged jet is about to turn upwards due to the weak hydraulic jump. This structure plays an important role in recovering the free surface to its original shape at a shorter downstream distance from the bluff body than when there is no gap.

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“…However, the extents of the near-and far-wake flow zones in Runs 1 and 2 are different because of the effects of dune dimensions. It is worth mentioning that in wall-wake flows downstream of a sphere and a horizontal cylinder, the velocity profiles appear to follow their corresponding undisturbed upstream velocity profile at streamwise distances equaling roughly 8.5 and 7 times the diameter of sphere and cylinder, respectively [12,21]. Figure 6 presents the vertical profiles of nondimensional Reynolds shear stress τ + (= τ/u 2 * ) at the upstream and various downstream relative streamwise distances x/L d in Runs 1 and 2.…”

Section: Experimental Designmentioning

confidence: 98%

“…The turbulence characteristics and the vortex shedding downstream of bed-mounted bluff-bodies in both near-and far-wake flows were studied by various researchers. Some of these bluff-bodies include plate [9,10], hemisphere [11], sphere [12,13], circular cylinder [14][15][16][17][18][19][20][21] and pebble cluster [22].…”

Section: Introductionmentioning

confidence: 99%

Turbulence in Wall-Wake Flow Downstream of an Isolated Dunal Bedform

Sarkar

Ali

Dey

2019

Water

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This study examines the turbulence in wall-wake flow downstream of an isolated dunal bedform. The streamwise flow velocity and Reynolds shear stress profiles at the upstream and various streamwise distances downstream of the dune were obtained. The results reveal that in the wall-wake flow, the third-order moments change their signs below the dune crest, whereas their signs remain unaltered above the crest. The near-wake flow is featured by sweep events, whereas the far-wake flow is controlled by the ejection events. Downstream of the dune, the turbulent kinetic energy production and dissipation rates, in the near-bed flow zone, are positive. However, they reduce as the vertical distance increases up to the lower-half of the dune height and beyond that, they increase with an increase in vertical distance, attaining their peaks at the crest. The turbulent kinetic energy diffusion and pressure energy diffusion rates, in the near-bed flow zone, are negative, whereas they attain their positive peaks at the crest. The anisotropy invariant maps indicate that the data plots in the wall-wake flow form a looping trend. Below the crest, the turbulence has an affinity to a two-dimensional isotropy, whereas above the crest, the anisotropy tends to reduce to a quasi-three-dimensional isotropy.

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Turbulence characteristics in wall-wake flows downstream of wall-mounted and near-wall horizontal cylinders

Cited by 16 publications

References 29 publications

Wake flow field of a wall-mounted pipe with spoiler on a rough channel bed

Wake flow field of a wall-mounted pipe with spoiler on a rough channel bed

Effect of gap on the flow characteristics in the wake of a bluff body near a wall

Turbulence in Wall-Wake Flow Downstream of an Isolated Dunal Bedform

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