TY  - JOUR
AB  - Purpose– The purpose of this paper is to discuss some fundamental aspects regarding the anomalies in the passive scalar field advected by forced homogenous and isotropic turbulence, by inspection of the analytical properties of the governing equations and with the aid of direct numerical simulation (DNS) data.Design/methodology/approach– Results from a pseudo‐spectral DNS of a unitary‐Schmidt‐ number passive scalar advected by a low Reynolds number flow field, Reλ=50 and 70 (based on the Taylor microscale λ) allow for a preliminary assessment of the developed numerical model.Findings– Manipulation of the governing equations for the scalar field (which are monotonic) reveals that the unboundedness of the scalar gradient magnitude is not ruled out by the mathematical properties of the correspondent conservation equation. Classic intermittency effects in the passive scalar field have been reproduced, such as non‐Gaussian behavior of the passive scalar statistics, loss of local isotropy, and multi‐fractal scaling of scalar structure functions. Moreover, Taylor and Richardson theories are, surprisingly, not confirmed only in the dissipation range (small‐scales anomalies).Originality/value– The authors suggest that the origin of intermittency (qualitatively pictured here as violent burst in spatial gradient quantities) should be sought in the loss of monotonicity of the evolution equation of the scalar gradient.
VL  - 23
IS  - 1
SN  - 0961-5539
DO  - 10.1108/09615531311289132
UR  - https://doi.org/10.1108/09615531311289132
AU  - Langella Ivan
AU  - Scalo Carlo
AU  - De Felice Giuseppe
AU  - Meola Carlo
ED  - X. Li
ED  - N. Massarotti
ED  - P. Nithiarasu
PY  - 2013
Y1  - 2013/01/01
TI  - Loss of monotonicity and anomalous scaling behavior in the passive scalar gradient: A DNS study on causes of intermittency
T2  - International Journal of Numerical Methods for Heat & Fluid Flow
PB  - Emerald Group Publishing Limited
SP  - 108
EP  - 123
Y2  - 2024/04/18
ER  -