Two-dimensional decaying turbulence in confined geometries

Tóth, Gábor; Házi, Gábor

doi:10.1142/s1793962314410086

Cited by 2 publications

(4 citation statements)

References 13 publications

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“…Here we extend previous LB studies [17,18,32] by introducing a random rough wall at one side of a rectangular domain and attempting to characterize the excess vorticity generated by collisions of vortices with such walls. Our ambition is to develop a methodology which might capture flow properties of oceanic surface currents near shorelines.…”

Section: Introductionmentioning

confidence: 88%

“…Since the basic formalism is summarized many times in the vast LB literature (see e.g., [8]), we do not reproduce here the standard equations quoted also in previous studies [17,18,31,32], instead we specify details of the present study.…”

Section: Lattice Boltzmann Simulationsmentioning

confidence: 99%

“…Particularly active areas of research are wall effects at high Reynolds numbers [15,20,22], or two-dimensional (2D) turbulence in bounded domains of various geometries [10][11][12]18,25,28,32,34]. As for B Imre M. Jánosi imre.janosi@ttk.elte.hu Gábor Tóth tooth@caesar.elte.hu the latter subject, Lattice Boltzmann (LB) method has proven to be specifically well suited to related numerical studies [1,3,8].…”

Section: Introductionmentioning

confidence: 99%

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Vorticity Generation by Rough Walls in 2D Decaying Turbulence

Tóth

Jánosi

2015

J Stat Phys

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In this work we present Lattice Boltzmann simulations of a decaying vortex array in a 2D rectangular domain, which is bounded by a random rough wall from one side. In order to separate the effects of the collisions with the rough wall, the opposite (smooth) rigid wall is placed at a larger distance from the center of the vortex array. Periodic boundary condition is imposed in the perpendicular direction. Well defined random roughness is generated by the widely studied Wolf-Villain surface growth algorithm. The main finding is that collisions with a rough wall generate excess vorticity compared with a smooth boundary, while the kinetic energy decreases monotonously. A proper measure is the integrated excess enstrophy, which exhibits an apparent maximum at an "optimal" roughness range. Numerical values of the excess enstrophy are very sensitive to a particular configuration (wall shape and vortex lattice randomization), however the "optimal" roughness exhibits surface features of similar characteristic sizes than that of the decaying vortices.

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Section: Introductionmentioning

confidence: 88%

Section: Lattice Boltzmann Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vorticity Generation by Rough Walls in 2D Decaying Turbulence

Tóth

Jánosi

2015

J Stat Phys

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“…The so called Lattice Boltzmann method (LBM) has proven to be specifically well suited for numerical studies of rigid wall bounded 2D turbulent flows [34,44]. Tóth and Jánosi [38] have recently extended previous LBM studies [13,14,36,37] on the interactions between freely decaying vortices and solid rough walls, therefore we can skip most technical details and restrict ourselves to the specific parameters of the presented simulations. We think that LBM simulations of freely decaying 2D turbulent flows provide a unique tool to clearly understand the physical link between vorticity generation and kinetic energy dissipation.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Large-scale vorticity generation and kinetic energy budget along the U.S. West Coast

Tóth,

Homonnai,

Jánosi

2017

Preprint

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We attempt to evaluate energy budget over a restricted but extremely well studied oceanic region along the shorelines of Oregon and California. The analysis is based on a recently updated geostrophic flow field data set covering 22 years with daily resolution on a grid of 0.25 • ×0.25 • , and turbulent wind stress data from the ERA-Interim reanalysis over the same geographic region with the same temporal and spatial resolutions. Integrated 2D kinetic energy, enstrophy, wind stress work and kinetic energy tendency are determined separately for the shore-and open water regions. The empirical analysis is supported by 2D lattice Boltzmann simulations of freely decaying vortices along a rough solid wall, which permits to separate the pure shoreline effects and dissipation properties of surface flow fields. Comparisons clearly demonstrate that kinetic energy and vorticity of the geostrophic flow field are mostly generated along the shorelines and advected to the open water regions, where the net wind stress work is almost negligible. Our results support that the geostrophic flow field is quasistationary on the timescale of a couple of days, thus total forcing is practically equal to total dissipation. Estimates of unknown terms in the equation of oceanic kinetic energy budget are based on other studies, nevertheless our results suggest that an effective eddy kinematic viscosity is in the order of magnitude 10 −2 m 2 /s along the shorelines, and it is lower by a factor of two in the open water region.

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Two-dimensional decaying turbulence in confined geometries

Cited by 2 publications

References 13 publications

Vorticity Generation by Rough Walls in 2D Decaying Turbulence

Vorticity Generation by Rough Walls in 2D Decaying Turbulence

Large-scale vorticity generation and kinetic energy budget along the U.S. West Coast

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