Numerical study on free surface flow of liquid metal lithium for IFMIF

The unsteady fully nonlinear free-surface flow due to an impulsively started submerged point sink is studied in the context of incompressible potential flow. For a fixed (initial) submergence h of the point sink in otherwise unbounded fluid, the problem is governed by a single non-dimensional physical parameter, the Froude number, [Fscr ]≡Q/4π(gh5)1/2, where Q is the (constant) volume flux rate and g the gravitational acceleration. We assume axisymmetry and perform a numerical study using a mixed-Eulerian–Lagrangian boundary-integral-equation scheme. We conduct systematic simulations varying the parameter [Fscr ] to obtain a complete quantification of the solution of the problem. Depending on [Fscr ], there are three distinct flow regimes: (i) [Fscr ]<[Fscr ]1≈0.1924 – a ‘sub-critical’ regime marked by a damped wave-like behaviour of the free surface which reaches an asymptotic steady state; (ii) [Fscr ]1<[Fscr ]<[Fscr ]2≈0.1930 – the ‘trans-critical’ regime characterized by a reversal of the downward motion of the free surface above the sink, eventually developing into a sharp upward jet; (iii) [Fscr ]>[Fscr ]2 – a ‘super-critical’ regime marked by the cusp-like collapse of the free surface towards the sink. Mechanisms behind such flow behaviour are discussed and hydrodynamic quantities such as pressure, power and force are obtained in each case. This investigation resolves the question of validity of a steady-state assumption for this problem and also shows that a small-time expansion may be inadequate for predicting the eventual behaviour of the flow.

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Experiments and Simulations of Free-Surface Flow behind a Finite Height Rigid Vertical Cylinder

Fluids ◽

10.3390/fluids6100367 ◽

2021 ◽

Vol 6 (10) ◽

pp. 367

Author(s):

Valentin Ageorges ◽

Jorge Peixinho ◽

Gaële Perret ◽

Ghislain Lartigue ◽

Vincent Moureau

Keyword(s):

Free Surface ◽

Numerical Study ◽

Three Dimensional ◽

Vertical Cylinder ◽

Free Surface Flow ◽

Air Entrainment ◽

Surface Flow ◽

Finite Height ◽

Wave Patterns ◽

Different Diameters

We present the results of a combined experimental and numerical study of the free-surface flow behind a finite height rigid vertical cylinder. The experiments measure the drag and the wake angle on cylinders of different diameters for a range of velocities corresponding to 30,000 <Re< 200,000 and 0.2<Fr<2 where the Reynolds and Froude numbers are based on the diameter. The three-dimensional large eddy simulations use a conservative level-set method for the air-water interface, thus predicting the pressure, the vorticity, the free-surface elevation and the onset of air entrainment. The deep flow looks like single phase turbulent flow past a cylinder, but close to the free-surface, the interaction between the wall, the free-surface and the flow is taking place, leading to a reduced cylinder drag and the appearance of V-shaped surface wave patterns. For large velocities, vortex shedding is suppressed in a layer region behind the cylinder below the free surface. The wave patterns mostly follow the capillary-gravity theory, which predicts the crest lines cusps. Interestingly, it also indicates the regions of strong elevation fluctuations and the location of air entrainment observed in the experiments. Overall, these new simulation results, drag, wake angle and onset of air entrainment, compare quantitatively with experiments.

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Thermal mixing enhancement of liquid metal MHD free-surface flow by optimizing vortex generator arrays

Fusion Engineering and Design ◽

10.1016/j.fusengdes.2018.01.067 ◽

2018 ◽

Vol 136 ◽

pp. 223-227 ◽

Cited By ~ 1

Author(s):

Koji Kusumi ◽

Tomoaki Kunugi ◽

Takehiko Yokomine ◽

Zensaku Kawara ◽

Shoki Nakamura ◽

...

Keyword(s):

Free Surface ◽

Liquid Metal ◽

Vortex Generator ◽

Free Surface Flow ◽

Surface Flow ◽

Mixing Enhancement ◽

Thermal Mixing

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Experimental and CFD Simulation Studies on the Free Surface Flow Behavior and Development in a Liquid Metal Windowless Target

Прикладная механика и техническая физика ◽

10.15372/pmtf20200312 ◽

2020 ◽

Vol 61 (3) ◽

pp. 110-119

Author(s):

W.-F. Yang ◽

W.-P. Deng ◽

X.-Y. Zhang

Keyword(s):

Free Surface ◽

Liquid Metal ◽

Cfd Simulation ◽

Flow Behavior ◽

Free Surface Flow ◽

Surface Flow ◽

Simulation Studies

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Study on Formation and Development of Surface Wave of Liquid Metal Lithium Jet for IFMIF

Volume 5: Fuel Cycle, Radioactive Waste Management and Decommissioning; Reactor Physics and Transport Theory; Nuclear Education, Public Acceptance and Related Issues; Instrumentation and Controls; Fusion Engineering ◽

10.1115/icone21-16689 ◽

2013 ◽

Author(s):

Eiji Hoashi ◽

Sachiko Yoshihashi-Suzuki ◽

Takafumi Okita ◽

Takuji Kanemura ◽

Hiroo Kondo ◽

...

Keyword(s):

Free Surface ◽

Surface Wave ◽

Liquid Metal ◽

Nozzle Exit ◽

Deuteron Beam ◽

Free Surface Flow ◽

Surface Flow ◽

Görtler Vortices ◽

Concave Wall ◽

Gortler Vortices

The international fusion materials irradiation facility (IFMIF) presents an intense neutron source to develop fusion reactor materials. The liquid metal Lithium (Li) jet with a free surface is planned as a target irradiated by two deuteron beam to generate intense neutrons and it is thus important to obtain information on the surface wave characteristic for the safety and the efficiency of system in the IFMIF. We have been studying on surface wave characteristics experimentally using the liquid metal Li circulation facility at Osaka University (Li loop) and numerically using computational fluid dynamics (CFD) code, FLUENT. The CFD simulation has been used in order to establish the mechanism of the formation and development of the surface wave of the liquid Li jet. The introduction of a two-staged contraction nozzle is planned in the IFMIF and the 1/2.5 size of the IFMIF’s nozzle has been also used and tested in our Li loop. These nozzles have a concave wall at each contraction part, and it was then predicted that Görtler vortices in the boundary layer inside the nozzle was generated and flowed out from the nozzle exit at the high velocity condition in our previous simulation. The Li free surface flow simulation including the flow inside the nozzle set in our Li loop was conducted to compare simulation results with experimental results and to evaluate the influence of Görtler vortices on the surface wave formation and development. In our simulation, large eddy simulation and volume of fluid models are used as turbulence model and interface tracking method, respectively. Our simulation result indicates that both transverse vortices due to gas-liquid shear stress and longitudinal vortices induced by Görtler vortices downstream the nozzle exit contribute to the formation of three-dimensional wave of the Li free surface flow at the velocity of 15 m/s. It was found that the vortex structure and the flow pattern under the free surface due to the flow inside the nozzle strongly contributed the development of the surface wave of the liquid Li jet.

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