Spectrum of a passive scalar in moderate Reynolds number homogenous isotropic turbulence

Title: Spectrum of a passive scalar in moderate Reynolds number homogenous isotropic turbulence
Creator: Danaila, L.; Antonia, R. A.
Relation: Physics of Fluids Vol. 21, Issue 11
Publisher Link: http://dx.doi.org/10.1063/1.3264881
Publisher: American Institute of Physics
Resource Type: journal article
Date: 2009
Description: For moderate Reynolds numbers, the spectral scaling exponents of both velocity [E(k)∞k−mu] and the transported passive scalar [Eθ(k)∞k−mθ] fields exhibit departures from the asymptotic prediction mu = mθ = 5/3. However, at the same Reynolds number, the passive scalar spectrum for homogeneous isotropic turbulence is closer to the universal asymptotic state than the dynamic velocity field that transports it. This paper provides a possible explanation for this behavior, in the case of a gaseous mixing with Prandtl (or Schmidt) number Pr ≃ 1. A scenario of the scalar energy transfer toward higher wavenumbers is proposed and validated using experimental data, in which the velocity field itself is actively involved via its characteristic time. A direct relationship between velocity and scalar spectra and therefore between mu and mθ is thus established.
Subject: gas mixtures; turbulence; homogenous isotropic turbulence; Reynolds numbers
Identifier: uon:6960
Identifier: http://hdl.handle.net/1959.13/925264
Identifier: ISSN:1070-6631
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