Understanding turbulent free-surface vortex flows using a Taylor-Couette flow analogy

Mulligan, Seán; Cesare, Giovanni De; Casserly, John; Sherlock, Richard

doi:10.1038/s41598-017-16950-w

Cited by 36 publications

(23 citation statements)

References 52 publications

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“…We consider the normal fluid velocity profile given by Eqs. (3) and 4, and we neglect the flow profile perturbation attributable to the quantized vortices generated through mutual friction. Microscopically, this assumption does not hold.…”

Section: Bundle Formation In Region IImentioning

confidence: 99%

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Bathtub vortex in superfluid He4

2020

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We have investigated the structure of macroscopic suction flows in superfluid 4 He. In this study, we primarily analyze the structure of the quantized vortex bundle that appears to play an important role in such systems. Our study is motivated by a series of recent experiments conducted by a research group at Osaka City University [Yano et al., J. Phys.: Conf. Ser. 969, 012002 (2018)]; they created a suction vortex using a rotor in superfluid 4 He. They also reported that up to 10 4 quantized vortices accumulated in the central region of the rotating flow. The quantized vortices in such macroscopic flows are assumed to form a bundle structure; however, the mechanism has not yet been fully investigated. Therefore, we prescribe a macroscopic suction flow to the normal fluid and discuss the evolution of a giant vortex (i.e., one with a circulation quantum number exceeding unity) and a bundle of singly quantized vortices from a small number of seed vortices. Then, using numerical simulations, we discuss several possible characteristic structures of the bundle in such a flow, and we suggest that the actual steady-state bundle structure in the experiment can be verified by measuring the diffusion constant of the vortex bundle after the macroscopic normal flow has been switched off. By applying extensive knowledge of the superfluid 4 He system, we elucidate a type of macroscopic superfluid flow and identify a structure of quantized vortices.

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Section: Bundle Formation In Region IImentioning

confidence: 99%

“…However, this vortex's simple generation procedure does not entail that its structure can be easily understood. Indeed, despite several attempts, no theory of the vortex has yet been completed [1][2][3]. In this paper, we elucidate the bathtub vortex from a different perspective: that of a bathtub vortex in superfluid 4 He.…”

Section: Introductionmentioning

confidence: 98%

Bathtub vortex in superfluid He4

2020

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“…A minor recirculation is also still present in the inlet channel. Slight water rotation can be observed around the funnel even though the incoming flow goes towards the funnel instead of around it [5]. Second part of the experiment, the vortex is present, slight water rotation around the funnel occurs, the inflowing jet is weakened due to the jump in water level (-----line) which allows a more uniform flow towards the funnel, water still slightly recirculates in the inflow zone 3.…”

Section: Flow Behaviormentioning

confidence: 98%

“…In order to avoid such costs in physical modelling in future studies, the purpose of this paper is to assess the validity of applying smoothed particle hydrodynamics (SPH) to vortex flows. Previous studies [5,6] show that, although it is possible to simulate free-surface vortices to within a respectable degree of accuracy using Eulerian multiphase approaches, the time required during the meshing process, not to mention computational power [5,6] to perform the simulations is discouraging. On the other hand, the DualSPHysics SPH code has been developed to study free-surface flow phenomena where Eulerian methods can be difficult to apply.…”

Section: Introductionmentioning

confidence: 99%

Vortex Siphon – From 1:1 Scale Physical Model to SPH Simulation and Prototype

Bart

Macherel

Cesare

et al. 2020

Advances in Hydroinformatics

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The rail link between Geneva Cornavin Station, Eaux-Vives Station and Annemasse (CEVA) is currently under construction including a cut-and-cover tunnel built by slurry walls located in the alluvium of the Foron River. The covered trench cuts the groundwater table flow which causes a rise of the water table on one side of the tunnel. Thirty wells were built in order to convey water from the aquifer on one side of the tunnel to the other. For each well, traditional pumping has been replaced by a self-priming multiphase siphon in order to lower energy costs. The operating principle of the system is based on the sustaining of a free-surface vortex flow in a vacuum chamber. In this way, the multiphase siphon is primed to allow water to be transferred from either side of the tunnel. A physical model of the conveyance system has been constructed at a scale of 1:1 in order to avoid scale effects from the presence of air water mixture and due to the free-surface vortices sensitivity to scaling, particularly in a vacuum atmosphere. In this study, the results from the physical model are used to validate a Smoothed Particle Hydrodynamics (SPH) numerical simulation of the complex flow conditions. The DualSPHysics code is employed and the results presented herein regarding the depth discharge relationship are encouraging for further application in vortex flows and such devices where conventional Eulerian modelling approaches can be challenging. As far as the authors are aware, this is the first application of SPH in simulating vortex chamber flows and the result bodes well for further application in this area.

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“…In case of energy production in a run-of-river power plant with a comparable small usable energy head, the inlet head losses and the velocity distribution in front of the turbine are key concerns in the design process [1][2][3]. Furthermore, the entrance of air and swirl can reduce the durability and the energy production of the turbine [4][5][6][7][8][9]. The entrance of animals or objects [10][11][12][13][14] has to be prevented for all hydro power plants (HPP) independently of the usable head.…”

Section: Generalmentioning

confidence: 99%

Adaptation of an Existing Intake Structure Caused by Increased Sediment Level

Gabl

Gems

Birkner

et al. 2018

Water

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An unexpected and massive redistribution of fine sediment in a large Alpine reservoir was triggered by a further lowering of the water level to conduct maintenance work. This caused the need of a total redesign of the existing head race intake for a high head power plant in the Austrian Alps. Two main geometry options for the trash rack support structure are compared with numerical simulations (ANSYS-CFX) as well as with a scale model test (scale 1:20). The laboratory experiment substantially benefited from the preliminary numerical investigation in respect of the location and implementation of the model boundaries. In return was the confidence in the numerics strengthened by the successful validation of the local head loss and the velocity distribution for the main operation cases. This allowed that the main inputs for the structural design and the further optimisation is conducted only with the 3D-numerical tool. The paper presents the interlaced concept as well as the main finding of the investigation, which lead to a successful adaptation of the intake structure.

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Understanding turbulent free-surface vortex flows using a Taylor-Couette flow analogy

Cited by 36 publications

References 52 publications

Bathtub vortex in superfluid He4

Bathtub vortex in superfluid He4

Vortex Siphon – From 1:1 Scale Physical Model to SPH Simulation and Prototype

Adaptation of an Existing Intake Structure Caused by Increased Sediment Level

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