Layered Structure of Stably Stratified Turbulent Shear Flows
- Authors: Glazunov A.V.1,2, Mortikov E.V.1,2, Barskov K.V.1,3, Kadantsev E.V.4, Zilitinkevich S.S.5,4
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Affiliations:
- Research Computing Center, Moscow State University
- Marchuk Institute of Numerical Mathematics, Russian Academy of Sciences
- Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences
- Institute for Atmospheric and Earth System Research, University of Helsinki
- Finnish Meteorological Institute
- Issue: Vol 55, No 4 (2019)
- Pages: 312-323
- Section: Article
- URL: https://journals.rcsi.science/0001-4338/article/view/148720
- DOI: https://doi.org/10.1134/S0001433819040042
- ID: 148720
Cite item
Abstract
Data of a numerical simulation of a stably stratified turbulent Couette flow are analyzed for various values of the Richardson number. Two different methods are used: direct numerical simulation (DNS) and large-eddy simulation (LES). It is shown that the flow contains large organized structures, along with chaotic turbulence, regardless of the simulation method. These structures appear as inclined layers in the temperature field with weakly stable stratification, separated by very thin layers with large temperature gradients. The existence of such layered structures in nature is indirectly confirmed by the analysis of data from field measurements on the meteorological mast, where temperature gradient histograms are found to be far from the normal distribution and similar to temperature gradient probability distributions obtained in numerical model data. The simulations indicate an increase in the turbulent Prandtl number with an increase in the gradient Richardson number. It is likely that the identified structures serve as efficient barriers for vertical turbulent heat flux without blocking the momentum transfer. We propose a hypothesis that it is these structures which serve as a physical mechanism for maintaining turbulence under supercritically stable stratification.
About the authors
A. V. Glazunov
Research Computing Center, Moscow State University; Marchuk Institute of Numerical Mathematics, Russian Academy of Sciences
Author for correspondence.
Email: and.glas@gmail.com
Russian Federation, Moscow, 119234; Moscow, 119991
E. V. Mortikov
Research Computing Center, Moscow State University; Marchuk Institute of Numerical Mathematics, Russian Academy of Sciences
Email: and.glas@gmail.com
Russian Federation, Moscow, 119234; Moscow, 119991
K. V. Barskov
Research Computing Center, Moscow State University; Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences
Email: and.glas@gmail.com
Russian Federation, Moscow, 119234; Moscow, 110017
E. V. Kadantsev
Institute for Atmospheric and Earth System Research, University of Helsinki
Email: and.glas@gmail.com
Finland, Helsinki
S. S. Zilitinkevich
Finnish Meteorological Institute; Institute for Atmospheric and Earth System Research, University of Helsinki
Email: and.glas@gmail.com
Finland, Helsinki; Helsinki