Shear effects on passive scalar spectra

Creators: Celani, A.; Cencini, M.; Vergassola, M.; Villermaux, Emmanuel; Vincenzi, D.

Others:: Institut Non Linéaire de Nice Sophia-Antipolis (INLN) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS); Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS); Center for Statistical Mechanics and Complexity ; Istituto Nazionale di Fisica Nucleare (INFN); Dipartimento di Fisica [Roma La Sapienza] ; Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome] (UNIROMA); Génomique des Microorganismes Pathogènes ; Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS); Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE) ; Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS); Laboratoire Jean Alexandre Dieudonné (JAD) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)

Description

The effects of a large-scale shear on the energy spectrum of a passively advected scalar field are investigated. The shear is superimposed on a turbulent isotropic flow, yielding an Obukhov-Corrsin $k^{-5/3}$ scalar spectrum at small scales. Shear effects appear at large scales, where a different, anisotropic behavior is observed. The scalar spectrum is shown to behave as $k^{-4/3}$ for a shear fixed in intensity and direction. For other types of shear characteristics, the slope is generally intermediate between the -5/3 Obukhov-Corrsin\'s and the -1 Batchelor\'s values. The physical mechanisms at the origin of this behaviour are illustrated in terms of the motion of Lagrangian particles. They provide an explanation to the scalar spectra shallow and dependent on the experimental conditions observed in shear flows at moderate Reynolds numbers.

Shear effects on passive scalar spectra

Description

Abstract

Abstract

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