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Numerical study of the return of axisymmetric turbulence to isotropy

Schumann, U. and Patterson, G.S. (1978) Numerical study of the return of axisymmetric turbulence to isotropy. Journal of Fluid Mechanics, 88, pp. 711-735. DOI: 10.1017/S0022112078002359

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Official URL: http://www.jfm.damtp.cam.ac.uk/

Abstract

The spectral method of Orszag and Patterson (1972a, b) is used here to study pressure and velocity fluctuations in axisymmetric, homogeneous, incompressible, decaying turbulence at Reynolds numbers Re<sub>λ</sub> [less, similar] 40. In real space 32<sup>3</sup> points are treated. The return to isotropy is simulated for several different sets of anisotropic Gaussian initial conditions. All contributions to the spectral energy balance for the different velocity components are shown as a function of time and wavenumber. The return to isotropy is effected by the pressure-strain correlation. The rate of return is larger at high than at low wavenumbers. The inertial energy transfer tends to create anisotropy at high wavenumbers. This explains the overrelaxation found by Herring (1974). The pressure and the inertial energy transfer are zero initially as the triple correlations are zero for the Gaussian initial values. The two transfer terms are independent of each other but vary with the same characteristic time scale. The pressure-strain correlation becomes small for extremely large anisotropies. This can be explained kinematically. Rotta's (1951) model is approximately valid if the anisotropy is small and if the time scale of the mean flow is much larger than 0·2 L<sub>f</sub>/v, which is the time scale of the triple correlations (L<sub>f</sub> = integral length scale, v = root-mean-square velocity). The value of Rotta's constant is less dependent upon the Reynolds number if the pressure-strain correlation is scaled by v<sup>3</sup>/L<sub>f</sub> rather than by the dissipation. Lumley and Khajeh-Nouri's (1974) model can be used to account for the influence of large anisotropies. The effect of strain is studied by splitting the total flow field into large- and fine-scale motion. The empirical model of Naot, Shavit and Wolfshtein (1970) has been confirmed in this respect.

Item URL in elib:https://elib.dlr.de/53666/
Document Type:Article
Title:Numerical study of the return of axisymmetric turbulence to isotropy
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Schumann, U.Kernforschungszentrum KarlsruheUNSPECIFIED
Patterson, G.S.NCAR, Boulder, CO, USAUNSPECIFIED
Date:1978
Journal or Publication Title:Journal of Fluid Mechanics
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:88
DOI :10.1017/S0022112078002359
Page Range:pp. 711-735
Status:Published
Keywords:spectral method
HGF - Research field:other
HGF - Program:other
HGF - Program Themes:other
DLR - Research area:no assignment
DLR - Program:no assignment
DLR - Research theme (Project):no assignment
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Deposited By: Freund, Jana
Deposited On:26 Nov 2008
Last Modified:31 Jul 2019 19:21

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