Dissipation and enstrophy in isotropic turbulence

Resolution effects and scaling in direct numerical simulations

D. A. Donzis, P. K. Yeung, K. R. Sreenivasan

Research output: Contribution to journalArticle

Abstract

Existing experimental and numerical data suggest that the turbulence energy dissipation and enstrophy (i.e., the square of vorticity) possess different scaling properties, while available theory suggests that there should be no differences at sufficiently high Reynolds numbers. We have performed a series of direct numerical simulations with up to 20483 grid points where advanced computational power is used to increase the Reynolds number (up to 650 on the Taylor scale) or to resolve the small scales better (down to 1/4 of a Kolmogorov scale). Our primary goal is to assess the differences and similarities between dissipation and enstrophy. Special attention is paid to the effects of small-scale resolution on the quality and reliability of the data, in view of recent theoretical work [V. Yakhot and K. R. Sreenivasan, "Anomalous scaling of structure functions and dynamic constraints on turbulence simulations," J. Stat. Phys. 121, 823 (2005)] which stipulates the resolution needed to obtain a moment of a given order.We also provide error estimates as a function of small-scale resolution. Probability density functions of dissipation and enstrophy at high Reynolds number reveal the presence of extreme events several thousands times of the mean. The extreme events in dissipation and enstrophy fields appear to scale alike, substantially overlap in space, and are nearly statistically isotropic, while fluctuations of moderate amplitudes, at least for the present Reynolds numbers, show persistent differences. Conditional sampling shows that intense dissipation is likely to be accompanied by similarly intense enstrophy, but intense enstrophy is not always accompanied by intense dissipation.

Original languageEnglish (US)
Article number045108
JournalPhysics of Fluids
Volume20
Issue number4
DOIs
StatePublished - Apr 2008

Fingerprint

isotropic turbulence
Direct numerical simulation
direct numerical simulation
vorticity
Reynolds number
Turbulence
dissipation
scaling
high Reynolds number
Vorticity
Probability density function
turbulence
Energy dissipation
Sampling
probability density functions
energy dissipation
sampling
grids
moments
estimates

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Dissipation and enstrophy in isotropic turbulence : Resolution effects and scaling in direct numerical simulations. / Donzis, D. A.; Yeung, P. K.; Sreenivasan, K. R.

In: Physics of Fluids, Vol. 20, No. 4, 045108, 04.2008.

Research output: Contribution to journalArticle

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