Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations

We report results on rotating stratified turbulence in the absence of forcing and with large-scale isotropic initial conditions using direct numerical simulations computed on grids of up to 40963 points. The Reynolds and Froude numbers are, respectively, equal to Re = 5.4 × 104 and Fr = 0.0242. The...

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Detalles Bibliográficos
Autor principal: Mininni, Pablo Daniel
Publicado: 2015
Materias:
Direct numerical simulation
Froude number
Numerical models
Reynolds number
Initial conditions
Large-scale dynamics
Localized vortices
Lower resolution
Richardson number
Spectral distribution
Stratified turbulence
Velocity and temperature fields
Turbulence
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10706631_v27_n5_p_Rosenberg
http://hdl.handle.net/20.500.12110/paper_10706631_v27_n5_p_Rosenberg
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_10706631_v27_n5_p_Rosenberg
record_format dspace
spelling paper:paper_10706631_v27_n5_p_Rosenberg2023-06-08T16:04:34Z Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations Mininni, Pablo Daniel Direct numerical simulation Froude number Numerical models Reynolds number Initial conditions Large-scale dynamics Localized vortices Lower resolution Richardson number Spectral distribution Stratified turbulence Velocity and temperature fields Turbulence We report results on rotating stratified turbulence in the absence of forcing and with large-scale isotropic initial conditions using direct numerical simulations computed on grids of up to 40963 points. The Reynolds and Froude numbers are, respectively, equal to Re = 5.4 × 104 and Fr = 0.0242. The ratio of the Brunt-Väisälä to the inertial wave frequency, N/ f, is taken to be equal to 4.95, a choice appropriate to model the dynamics of the southern abyssal ocean at mid latitudes. This gives a global buoyancy Reynolds number R<inf>B</inf> = ReFr2 ≈ 32, a value sufficient for some isotropy to be recovered in the small scales beyond the Ozmidov scale, but still moderate enough that the intermediate scales where waves are prevalent are well resolved. We concentrate on the large-scale dynamics, for which we find a spectrum compatible with the Bolgiano-Obukhov scaling. This scaling is also found for geostrophically balanced initial conditions on a run at a lower resolution and hence lower R<inf>B</inf> ≈ 4. Furthermore, we confirm that the Froude number based on a typical vertical length scale is of order unity, with strong gradients in the vertical. Two characteristic scales emerge from this computation and are identified from sharp variations in the spectral distribution of either total energy or helicity. A spectral break is also observed at a scale at which the partition of energy between the kinetic and potential modes changes abruptly, and beyond which a Kolmogorov-like spectrum recovers. Large slanted layers are ubiquitous in the flow, in the velocity and temperature fields, with local overturning events indicated by small local Richardson numbers and strong localized vortex tangles. Finally, a small large-scale enhancement of energy directly attributable to the effect of rotation is also observed. © 2015 AIP Publishing LLC. Fil:Mininni, P.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10706631_v27_n5_p_Rosenberg http://hdl.handle.net/20.500.12110/paper_10706631_v27_n5_p_Rosenberg
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Direct numerical simulation
Froude number
Numerical models
Reynolds number
Initial conditions
Large-scale dynamics
Localized vortices
Lower resolution
Richardson number
Spectral distribution
Stratified turbulence
Velocity and temperature fields
Turbulence
spellingShingle Direct numerical simulation
Froude number
Numerical models
Reynolds number
Initial conditions
Large-scale dynamics
Localized vortices
Lower resolution
Richardson number
Spectral distribution
Stratified turbulence
Velocity and temperature fields
Turbulence
Mininni, Pablo Daniel
Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations
topic_facet Direct numerical simulation
Froude number
Numerical models
Reynolds number
Initial conditions
Large-scale dynamics
Localized vortices
Lower resolution
Richardson number
Spectral distribution
Stratified turbulence
Velocity and temperature fields
Turbulence
description We report results on rotating stratified turbulence in the absence of forcing and with large-scale isotropic initial conditions using direct numerical simulations computed on grids of up to 40963 points. The Reynolds and Froude numbers are, respectively, equal to Re = 5.4 × 104 and Fr = 0.0242. The ratio of the Brunt-Väisälä to the inertial wave frequency, N/ f, is taken to be equal to 4.95, a choice appropriate to model the dynamics of the southern abyssal ocean at mid latitudes. This gives a global buoyancy Reynolds number R<inf>B</inf> = ReFr2 ≈ 32, a value sufficient for some isotropy to be recovered in the small scales beyond the Ozmidov scale, but still moderate enough that the intermediate scales where waves are prevalent are well resolved. We concentrate on the large-scale dynamics, for which we find a spectrum compatible with the Bolgiano-Obukhov scaling. This scaling is also found for geostrophically balanced initial conditions on a run at a lower resolution and hence lower R<inf>B</inf> ≈ 4. Furthermore, we confirm that the Froude number based on a typical vertical length scale is of order unity, with strong gradients in the vertical. Two characteristic scales emerge from this computation and are identified from sharp variations in the spectral distribution of either total energy or helicity. A spectral break is also observed at a scale at which the partition of energy between the kinetic and potential modes changes abruptly, and beyond which a Kolmogorov-like spectrum recovers. Large slanted layers are ubiquitous in the flow, in the velocity and temperature fields, with local overturning events indicated by small local Richardson numbers and strong localized vortex tangles. Finally, a small large-scale enhancement of energy directly attributable to the effect of rotation is also observed. © 2015 AIP Publishing LLC.
author Mininni, Pablo Daniel
author_facet Mininni, Pablo Daniel
author_sort Mininni, Pablo Daniel
title Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations
title_short Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations
title_full Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations
title_fullStr Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations
title_full_unstemmed Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations
title_sort evidence for bolgiano-obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations
publishDate 2015
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10706631_v27_n5_p_Rosenberg
http://hdl.handle.net/20.500.12110/paper_10706631_v27_n5_p_Rosenberg
work_keys_str_mv AT mininnipablodaniel evidenceforbolgianoobukhovscalinginrotatingstratifiedturbulenceusinghighresolutiondirectnumericalsimulations
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