Challenges in modeling scalars in turbulence and LES: Anisotropy, dynamic models, and scale separation

C. Meneveau, H. S. Kang, F. Charlette, J. Averill, Omar Knio, D. Veynante

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

This paper discusses three interrelated aspects of modeling scalar transport, mixing and combustion, in the context of large-eddy simulations (LES). In terms of passive scalar modeling, we find from heated wake measurements that whereas the kinetic energy dissipation tensor tends towards isotropy at small scales, in the presence of a mean scalar gradient the SGS scalar variance dissipation remains anisotropic independent of filter scale. The eddy-diffusion model predicts isotropic behavior, whereas the nonlinear model reproduces the correct trends, but overestimates the level of scalar dissipation anisotropy. The results provide some support for mixed models. Applications of dynamic models are also discussed. Initial tests on non-buoyant jet flows show that the constant-coefficient Smagorinsky model generates an entirely laminar jet, whereas the Lagrangian dynamic model yields very good results without the need to tune the model coefficient. In the context of applying the dynamic model to premixed combustion, or other physical processes with large scale-separations, we show that the dynamic determination of unknown scaling exponents is a more promising approach than dynamic evaluation of model coefficients.

Original languageEnglish (US)
Title of host publicationIUTAM Symposium on Turbulent Mixing and Combustion - Proceedings of the IUTAM Symposium
Pages181-199
Number of pages19
DOIs
StatePublished - Dec 1 2002
EventInternational Union of Theoretical and Applied Mechanics Symposium on Turbulent Mixing and Combustion - Kingston, ON, Canada
Duration: Jun 3 2001Jun 6 2001

Publication series

NameFluid Mechanics and its Applications
Volume70
ISSN (Print)0926-5112

Other

OtherInternational Union of Theoretical and Applied Mechanics Symposium on Turbulent Mixing and Combustion
CountryCanada
CityKingston, ON
Period06/3/0106/6/01

Keywords

  • Dynamic model
  • LES
  • Modeling
  • Passive scalar anisotropy
  • Premixed combustion
  • Scale separation

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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