Direct Numerical Simulation of Turbulent Flow in a Square Duct: Analysis of Secondary Flows

Joung, Younghoon; Choi, Sung Uk; Choi, Jung Il

doi:10.1061/(asce)0733-9399(2007)133:2(213)

Cited by 36 publications

(25 citation statements)

References 23 publications

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“…Near the lower corner, a pair of counter-rotating secondary flows is observed, which are nearly symmetric along the corner bisector. These bottom secondary flows are similar to those observed in turbulent square duct flows by Gavrilakis [11], Huser and Biringen [14], and Joung et al [24]. Near the upper corner, another pair of counterrotating vortices is observed.…”

Section: Mean Flow Properties and Turbulence Structuressupporting

confidence: 87%

“…In the figure, the positive and negative values are denoted by solid and dashed lines, respectively. It can be seen that the distributions of all Reynolds stress components in the region away from the free surface are similar to those for square duct flows reported by Huser and Biringen [14] and Joung et al [24]. However, near the free surface, the distributions are different due to the free surface effect.…”

Section: Mean Flow Properties and Turbulence Structuressupporting

confidence: 81%

“…Figure 10 presents the surface-normal distributions for Reynolds shear stress estimated at three planes (y/H = 0.054, 0.236, and 0.5) using the DNS data. Joung et al [24] carried out a DNS of turbulent flow in a square duct. Using the conditional quadrant analysis of the DNS data, they concluded that the patterns of the secondary flows are determined by the directional tendency of coherent structures.…”

Section: Mean Flow Properties and Turbulence Structuresmentioning

confidence: 99%

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Direct numerical simulation of low Reynolds number flows in an open‐channel with sidewalls

Joung¹,

Choi

2009

Numerical Methods in Fluids

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SUMMARYA direct numerical simulation of low Reynolds number turbulent flows in an open-channel with sidewalls is presented. Mean flow and turbulence structures are described and compared with both simulated and measured data available from the literature. The simulation results show that secondary flows are generated near the walls and free surface. In particular, at the upper corner of the channel, a small vortex called inner secondary flows is simulated. The results show that the inner secondary flows, counter-rotating to outer secondary flows away from the sidewall, increase the shear velocity near the free surface. The secondary flows observed in turbulent open-channel flows are related to the production of Reynolds shear stress. A quadrant analysis shows that sweeps and ejections are dominant in the regions where secondary flows rush in toward the wall and eject from the wall, respectively. A conditional quadrant analysis also reveals that the production of Reynolds shear stress and the secondary flow patterns are determined by the directional tendency of the dominant coherent structures.

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Section: Mean Flow Properties and Turbulence Structuressupporting

confidence: 87%

Section: Mean Flow Properties and Turbulence Structuressupporting

confidence: 81%

Section: Mean Flow Properties and Turbulence Structuresmentioning

confidence: 99%

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Direct numerical simulation of low Reynolds number flows in an open‐channel with sidewalls

Joung¹,

Choi

2009

Numerical Methods in Fluids

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“…Thereby, the velocity profiles are not fully developed at the nozzle exit and the turbulent intensities are of ∼10-20%, which is approximately two times the intensity found in fully developed turbulent flows in a square duct at a similar Reynolds number (see e.g., [56,57]). Furthermore, it is apparent, that measured inflow mean and rms velocity profiles differ slightly for different inclination angles, especially at the side facing the solid wall.…”

Section: Appendix B Inflow Conditions For Numerical Simulationsmentioning

confidence: 88%

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Ries

Rißmann

et al. 2018

Fluids

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Abstract:In the present paper, direct numerical simulation (DNS) and particle image velocimetry (PIV) have been applied complementarily in order to generate a database of near-wall turbulence properties of a highly turbulent jet impinging on a solid surface under different inclination angles. Thereby, the main focus is placed on an impingement angle of 45 • , since it represents a good generic benchmark test case for a wide range of technical fluid flow applications. This specific configuration features very complex flow properties including the presence of a stagnation point, development of the shear boundary layer and strong streamline curvature. In particular, this database includes near-wall turbulence statistics along with mean and rms velocities, budget terms in the turbulent kinetic energy equation, anisotropy invariant maps, turbulent length/time scales and near-wall shear stresses. These properties are useful for the validation of near-wall modeling approaches in the context of Reynolds-averaged Navier-Stokes (RANS) and large-eddy simulations (LES). From this study, in which further impingement angles (0 • , 90 • ) have been considered in the experiments only, it turns out that (1) the production of turbulent kinetic energy appears negative at the stagnation point for an impingement angle other than 0 • and is balanced predominantly by pressure-related diffusion, (2) quasi-coherent thin streaks with large characteristic time scales appear at the stagnation region, while the organization of the flow is predominantly toroidal further downstream, and (3) near-wall shear stresses are low at the stagnation region and intense in regions where the direction of the flow changes suddenly.

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“…Another key finding from the simulation, which is a consequence of these wall shear stress gradients, was that the streamwise velocity profile along the wall bisector exhibited an overshoot from the well-known logarithmic law (u + = 2.5 ln y + + 5.5) in the overlap layer when normalised by the average (across the duct perimeter) rather than local friction velocity, u τ = √ τ w /ρ, where ρ is the density. Other researchers who have conducted DNS of square duct turbulent flow and obtained similar results include Huser & Biringen (1993) and Joung, Choi & Choi (2007).…”

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confidence: 63%

Experiments on low-Reynolds-number turbulent flow through a square duct

2016

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Previous experimental studies on turbulent square duct flow have focused mainly on high Reynolds numbers for which a turbulence-induced eight-vortex secondary flow pattern exists in the cross-sectional plane. More recently, direct numerical simulations (DNS) have revealed that the flow field at Reynolds numbers close to transition can be very different; the flow in this 'marginally turbulent' regime alternating between two states characterised by four vortices. In this study, we experimentally investigate the onset criteria for transition to turbulence in square ducts. In so doing, we highlight the potential importance of Coriolis effects on this process for low-Ekman-number flows. We also present experimental data on the mean flow properties and turbulence statistics in both marginally and fully turbulent flow at relatively low Reynolds numbers using laser Doppler velocimetry. Results for both flow categories show good agreement with DNS. The switching of the flow field between two flow states at marginally turbulent Reynolds numbers is confirmed by bimodal probability density functions of streamwise velocity at certain distances from the wall as well as joint probability density functions of streamwise and wall normal velocities which feature two peaks highlighting the two states.

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Direct Numerical Simulation of Turbulent Flow in a Square Duct: Analysis of Secondary Flows

Cited by 36 publications

References 23 publications

Direct numerical simulation of low Reynolds number flows in an open‐channel with sidewalls

Direct numerical simulation of low Reynolds number flows in an open‐channel with sidewalls

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Experiments on low-Reynolds-number turbulent flow through a square duct

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