Exact Intermittent Solutions in a Turbulence Multi-Branch Shell Model

Reproducing complex phenomena with simple models marks our understanding of the phenomena themselves, and this is what Jack Herring’s work demonstrated multiple times. In that spirit, this work studies a turbulence shell model consisting of a hierarchy of structures of different scales <inline-fo...

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Main Authors: Ben Ajzner, Alexandros Alexakis
Format: Article
Language:English
Published: MDPI AG 2023-08-01
Series:Atmosphere
Subjects:
Online Access:https://www.mdpi.com/2073-4433/14/8/1316
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author Ben Ajzner
Alexandros Alexakis
author_facet Ben Ajzner
Alexandros Alexakis
author_sort Ben Ajzner
collection DOAJ
description Reproducing complex phenomena with simple models marks our understanding of the phenomena themselves, and this is what Jack Herring’s work demonstrated multiple times. In that spirit, this work studies a turbulence shell model consisting of a hierarchy of structures of different scales <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mi>n</mi></msub></semantics></math></inline-formula> such that each structure transfers its energy to two substructures of scale <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mo>ℓ</mo><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>=</mo><msub><mo>ℓ</mo><mi>n</mi></msub><mo>/</mo><mi>λ</mi></mrow></semantics></math></inline-formula>. For this model, we construct exact inertial range solutions that display intermittency, i.e., absence of self-similarity. Using a large ensemble of these solutions, we investigate how the probability distributions of the velocity modes change with scale. It is demonstrated that, while velocity amplitudes are not scale-invariant, their ratios are. Furthermore, using large deviation theory, we show how the probability distributions of the velocity modes can be re-scaled to collapse in a scale-independent form. Finally, we discuss the implications the present results have for real turbulent flows.
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spelling doaj.art-86e8c7ff7ebb49c6890efbed62569bba2023-11-19T00:13:44ZengMDPI AGAtmosphere2073-44332023-08-01148131610.3390/atmos14081316Exact Intermittent Solutions in a Turbulence Multi-Branch Shell ModelBen Ajzner0Alexandros Alexakis1Laboratoire de Physique de l’Ecole Normale Supérieure, Université PSL, Centre National de la Recherche Scientifique, Sorbonne Université, Université de Paris, F-75005 Paris, FranceLaboratoire de Physique de l’Ecole Normale Supérieure, Université PSL, Centre National de la Recherche Scientifique, Sorbonne Université, Université de Paris, F-75005 Paris, FranceReproducing complex phenomena with simple models marks our understanding of the phenomena themselves, and this is what Jack Herring’s work demonstrated multiple times. In that spirit, this work studies a turbulence shell model consisting of a hierarchy of structures of different scales <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mo>ℓ</mo><mi>n</mi></msub></semantics></math></inline-formula> such that each structure transfers its energy to two substructures of scale <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mo>ℓ</mo><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>=</mo><msub><mo>ℓ</mo><mi>n</mi></msub><mo>/</mo><mi>λ</mi></mrow></semantics></math></inline-formula>. For this model, we construct exact inertial range solutions that display intermittency, i.e., absence of self-similarity. Using a large ensemble of these solutions, we investigate how the probability distributions of the velocity modes change with scale. It is demonstrated that, while velocity amplitudes are not scale-invariant, their ratios are. Furthermore, using large deviation theory, we show how the probability distributions of the velocity modes can be re-scaled to collapse in a scale-independent form. Finally, we discuss the implications the present results have for real turbulent flows.https://www.mdpi.com/2073-4433/14/8/1316turbulenceintermittency
spellingShingle Ben Ajzner
Alexandros Alexakis
Exact Intermittent Solutions in a Turbulence Multi-Branch Shell Model
Atmosphere
turbulence
intermittency
title Exact Intermittent Solutions in a Turbulence Multi-Branch Shell Model
title_full Exact Intermittent Solutions in a Turbulence Multi-Branch Shell Model
title_fullStr Exact Intermittent Solutions in a Turbulence Multi-Branch Shell Model
title_full_unstemmed Exact Intermittent Solutions in a Turbulence Multi-Branch Shell Model
title_short Exact Intermittent Solutions in a Turbulence Multi-Branch Shell Model
title_sort exact intermittent solutions in a turbulence multi branch shell model
topic turbulence
intermittency
url https://www.mdpi.com/2073-4433/14/8/1316
work_keys_str_mv AT benajzner exactintermittentsolutionsinaturbulencemultibranchshellmodel
AT alexandrosalexakis exactintermittentsolutionsinaturbulencemultibranchshellmodel