Large eddy simulation of temporally developing juncture flows

Sreedhar, Madhu; Stern, Fred

doi:10.1002/(sici)1097-0363(19980715)28:1<47::aid-fld698>3.0.co;2-p

Cited by 10 publications

(22 citation statements)

References 35 publications

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“…Some of the conclusions of Longo et al (1998) and Sreedhar & Stern (1998) also appear to be in conflict with the results obtained by the follow-up experimental study of the same problem by Hsu et al (2000), suggesting that the dynamics of boundarylayer/free-surface juncture have not been perfectly elucidated. Furthermore, certain issues were not fully addressed owing to limitations of experimental investigations, for example the resolution of the flow very near the free surface.…”

Section: Introductionmentioning

confidence: 84%

“…In these simulations, in which the inner secondary flow was resolved, the TKE increased near the rigid-lid boundary and a redistribution of energy from the surface normal components to the other two was also observed in this region. There is some controversy on this issue, since Longo et al (1998) and Sreedhar & Stern (1998) predict an increase of mean-square streamwise velocity fluctuations as the distance from the free surface decreases, while Grega et al (1995), in their experiments, measure an increase in this quantity. Similar discrepancies are found in the behaviour of the anisotropy-tensor profiles.…”

Section: Introductionmentioning

confidence: 99%

“…The existence of mean secondary flows in the corner (similar to those that occur in the closed ducts) adds complexity to the problem. Studies of turbulent flows in the corner formed by a vertical solid wall and a free surface have been performed, among others, by Grega et al (1995), Longo, Huang & Stern (1998), Sreedhar & Stern (1998), Hsu et al (2000) and Grega, Hsu & Wei (2002). Grega et al (1995) carried out numerical simulations in conjuction with experimental flow visualization and single-component laser-Doppler anemometry (LDA) velocity measurements.…”

Section: Introductionmentioning

confidence: 99%

“…However, in this case also, the marginal measurement resolution did not permit visualization of the inner secondary vortex motion. Sreedhar & Stern (1998) carried out large-eddy simulations (LES) of compressible temporally developing solid/solid and solid/rigid-lid corner flows. In these simulations, in which the inner secondary flow was resolved, the TKE increased near the rigid-lid boundary and a redistribution of energy from the surface normal components to the other two was also observed in this region.…”

Section: Introductionmentioning

confidence: 99%

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Large-eddy simulations of ducts with a free surface

2003

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This work studies the momentum and energy transport mechanisms in the corner between a free surface and a solid wall. We perform large-eddy simulations of the incompressible fully developed turbulent flow in a square duct bounded above by a free-slip wall, for Reynolds numbers based on the mean friction velocity and the duct width equal to 360, 600 and 1000. The flow in the corner is strongly affected by the advection due to two counter-rotating secondary-flow regions present immediately below the free surface. Because of the convection of the inner eddy, as the free surface is approached, the friction velocity on the sidewall first decreases, then increases again. A similar behaviour is observed for the surface-parallel Reynolds-stress components, which first decrease and then increase again very close to the surface. The budgets of the Reynolds stresses show a strong reduction of all terms of the dissipation tensor in both the inner and outer near-corner regions. They exhibit a reduction in both production and dissipation towards the free surface. Very close to the solid boundary, within 15-20 viscous lengths of the sidewall, the turbulent kinetic energy production and the surface-parallel fluctuations rebound in the thin layer adjacent to the free surface. The Reynolds-stress anisotropy appears to be the main factor in the generation of the mean secondary flow. The multi-layer structure of the boundary layer near the free surface is also discussed.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Large-eddy simulations of ducts with a free surface

2003

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“…In the last few years, turbulence associated with the horizontal flow of water along a vertical wall in the vicinity of a horizontal free surface, the 'mixed-boundary corner', has received much of attention. Examples of recent works include experimental studies by Grega et al (1995), Longo, Huang & Stern (1998), and Hsu et al (2000), and large-eddy simulation studies by Thomas & William (1995) and Sreedhar & Stern (1998). The motivation for these studies ranged from modelling ship wakes through transport in rivers and channels, to anisotropies in manufacturing processes such as papermaking.…”

Section: Introductionmentioning

confidence: 99%

Vorticity transport in a corner formed by a solid wall and a free surface

2002

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There is a growing body of literature in which turbulent boundary layer flow along a mixed-boundary corner formed by a vertical solid wall and a horizontal free surface has been examined. While there is consensus regarding the existence of weak secondary flows in the near corner region, there is some disagreement as to the exact nature and origin of these flows. In two earlier works by the authors, evidence was presented supporting the existence of a weak streamwise vortex which rotates in toward the wall at the free surface and down away from the surface along the wall. This ‘inner secondary vortex’ is accompanied by an ‘outer secondary flow’ which transports low-momentum boundary layer fluid up along the wall and outward at the free surface. The magnitudes of the cross-stream velocities associated with these secondary flows were measured to be on the order of 1% of the free-stream speed. In this paper, high-resolution DPIV measurements made in the cross-stream plane are presented. These clearly show the inner and outer secondary flows. The cross-stream vector fields allow computation of terms in the turbulent streamwise vorticity transport equation. These terms indicate mean vorticity transport at the free surface associated with the outer secondary flow. In addition there appears to be a balance between the wall-normal and free-surface-normal fluctuating vorticity reorientation terms.

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