Numerical simulation of bubble-type vortex breakdown within a tube-and-vane apparatus

Snyder, Deryl O.; Spall, Robert E.

doi:10.1063/1.870266

Cited by 34 publications

(17 citation statements)

References 16 publications

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“…Besides e.g. the work by Spall and co-workers [31,32], this is one of the first reports of three-dimensional simulation of turbulent vortex breakdown in conjunction with experimental validation.…”

Section: Discussionmentioning

confidence: 99%

Simulations of confined turbulent vortex flow

Derksen

2005

Computers & Fluids

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Large-eddy simulations (LES) of the turbulent flow in a swirl tube with a tangential inlet have been performed. The geometry, and flow conditions were chosen according to an experimental study by [Escudier MP, Bornstein J, Zehnder N. Observations and LDA measurements of confined turbulent vortex flow. J Fluid Mech 1980;98:49-63]. Lattice-Boltzmann discretization was used to numerically solve the Navier-Stokes equations in the incompressible limit. Effects of spatial resolution and choices in subgridscale modeling were explicitly investigated with the experimental data set as the testing ground. Experimentally observed flow features, such as vortex breakdown and laminarization of the vortex core were well represented by the LES. The simulations confirmed the experimental observations that the average velocity profiles in the entire vortex tube are extremely sensitivity to the exit pipe diameter. For the narrowest exit pipe considered in the simulations, very high average velocity gradients are encountered. In this situation, the LES shows the most pronounced effects of spatial resolution and subgrid-scale modeling.

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Section: Discussionmentioning

confidence: 99%

Simulations of confined turbulent vortex flow

Derksen

2005

Computers & Fluids

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“…Another problem is that in some studies the circulation further downstream actually exceeds that predicted by equation (3.4) by a significant margin. For example, the experimental data of Faler & Leibovich (1978) indicates an overshoot of 38% while there is an overshoot of 26% in the numerical simulation of a complete guide vane apparatus by Snyder & Spall (2000). Figure 2 compares the circulation measured outside the vortex core and wall boundary layers with the estimate from equation (3.4).…”

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confidence: 99%

Vortical flow. Part 1. Flow through a constant-diameter pipe

2002

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This paper describes an exploration of the behaviour and properties of swirling flow through a constant-diameter pipe. The experiments reveal a complicated transition process as the swirl intensity Ω is increased at fixed pipe Reynolds number Re ≈ 4900.For Ω 6 1.09, the vortex was steady, laminar, axisymmetric, and developed slowly with streamwise distance. The upstream velocity profiles were similar to those commonly appearing in the literature in similar apparatus. Spiral vortex breakdown appeared in the test section for 1.09 6 Ω 6 1.31 and was associated with a localized transition from jet-like to wake-like mean axial velocity profiles. Further increase in Ω caused the breakdown to move upstream of the test section. Downstream, the core of the post-breakdown flow was unsteady and recovered toward jet-like profiles with streamwise distance. At Ω = 2.68, a global transition occurred in which the mean axial velocity profiles suddenly developed an annular axial velocity deficit. At the same time, disturbances began to appear in the outer flow. Further increase in Ω eventually led to an annulus of reversed axial flow and a completely unsteady vortex.

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“…The reason for this inconsistent behaviour is not known; however it is worthwhile pointing out that overshoots are not uncommon. The experimental data of Faler & Leibovich (1978) indicate an overshoot of 38%, while there is an overshoot of 26% in the numerical simulation by Snyder & Spall (2000). Such behaviour makes Ω, as defined by equations (3.3) and (3.4), somewhat unreliable as a flow parameter.…”

Section: Circulation and Stream Functionmentioning

confidence: 95%

Vortical flow. Part 2. Flow past a sphere in a constant-diameter pipe

2003

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This paper describes an experimental and numerical investigation of concentrated vortex flow past a sphere in a constant-diameter pipe. As the swirl was increased at a fixed sphere Reynolds number of approximately 1100, the length of the mean downstream separation bubble decreased. For a small range of swirl intensity, an almost stagnant separation bubble formed on the upstream hemisphere. A further increase in swirl caused the bubble to become unstable and develop into an unsteady spiral disturbance. At very high swirl the downstream separation bubble was eliminated and an unsteady separation zone extended far upstream. Calculations of the vorticity field from surface fits to azimuthal and axial velocity data suggest that upstream separation is caused by the distortion of vortex filaments in the diverging flow approaching the sphere. Numerical solutions of steady inviscid axisymmetric flow past a sphere exhibit a fold in the vicinity of upstream separation. It is suggested that this accounts for the extreme sensitivity encountered in the experiments.

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Numerical simulation of bubble-type vortex breakdown within a tube-and-vane apparatus

Cited by 34 publications

References 16 publications

Simulations of confined turbulent vortex flow

Simulations of confined turbulent vortex flow

Vortical flow. Part 1. Flow through a constant-diameter pipe

Vortical flow. Part 2. Flow past a sphere in a constant-diameter pipe

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