Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number

We investigate the large-scale intermittency of vertical velocity and temperature, and the mixing properties of stably stratified turbulent flows using both Lagrangian and Eulerian fields from direct numerical simulations of the Boussinesq equations with periodic boundary conditions, in a parameter...

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Detalles Bibliográficos
Autores principales:	Feraco, F., Marino, R., Pumir, A., Primavera, L., Mininni, P.D., Pouquet, A., Rosenberg, D.
Formato:	JOUR
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_02955075_v123_n4_p_Feraco
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_02955075_v123_n4_p_Feraco
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spelling	todo:paper_02955075_v123_n4_p_Feraco2023-10-03T15:17:23Z Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number Feraco, F. Marino, R. Pumir, A. Primavera, L. Mininni, P.D. Pouquet, A. Rosenberg, D. We investigate the large-scale intermittency of vertical velocity and temperature, and the mixing properties of stably stratified turbulent flows using both Lagrangian and Eulerian fields from direct numerical simulations of the Boussinesq equations with periodic boundary conditions, in a parameter space relevant for the atmosphere and the oceans. Over a range of Froude numbers of geophysical interest (≈ 0.05-0.3) we observe very large fluctuations of the vertical components of the velocity and the potential temperature, localized in space and time, with a sharp transition leading to non-Gaussian wings of the probability distribution functions. This behavior is captured by a simple model representing the competition between gravity waves on a fast time scale and nonlinear steepening on a slower time scale. The existence of a resonant regime characterized by enhanced large-scale intermittency, as understood within the framework of the proposed model, is then linked to the emergence of structures in the velocity and potential temperature fields, localized overturning and mixing. Finally, in the same regime we observe a linear scaling of the mixing efficiency with the Froude number and an increase of its value of roughly one order of magnitude. © EPLA, 2018. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_02955075_v123_n4_p_Feraco
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description	We investigate the large-scale intermittency of vertical velocity and temperature, and the mixing properties of stably stratified turbulent flows using both Lagrangian and Eulerian fields from direct numerical simulations of the Boussinesq equations with periodic boundary conditions, in a parameter space relevant for the atmosphere and the oceans. Over a range of Froude numbers of geophysical interest (≈ 0.05-0.3) we observe very large fluctuations of the vertical components of the velocity and the potential temperature, localized in space and time, with a sharp transition leading to non-Gaussian wings of the probability distribution functions. This behavior is captured by a simple model representing the competition between gravity waves on a fast time scale and nonlinear steepening on a slower time scale. The existence of a resonant regime characterized by enhanced large-scale intermittency, as understood within the framework of the proposed model, is then linked to the emergence of structures in the velocity and potential temperature fields, localized overturning and mixing. Finally, in the same regime we observe a linear scaling of the mixing efficiency with the Froude number and an increase of its value of roughly one order of magnitude. © EPLA, 2018.
format	JOUR
author	Feraco, F. Marino, R. Pumir, A. Primavera, L. Mininni, P.D. Pouquet, A. Rosenberg, D.
spellingShingle	Feraco, F. Marino, R. Pumir, A. Primavera, L. Mininni, P.D. Pouquet, A. Rosenberg, D. Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number
author_facet	Feraco, F. Marino, R. Pumir, A. Primavera, L. Mininni, P.D. Pouquet, A. Rosenberg, D.
author_sort	Feraco, F.
title	Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number
title_short	Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number
title_full	Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number
title_fullStr	Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number
title_full_unstemmed	Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number
title_sort	vertical drafts and mixing in stratified turbulence: sharp transition with froude number
url	http://hdl.handle.net/20.500.12110/paper_02955075_v123_n4_p_Feraco
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Vertical drafts and mixing in stratified turbulence: Sharp transition with Froude number

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