Development of similarity relationships for energy dissipation rate and temperature structure parameter in stably stratified flows: a direct numerical simulation approach

Ping He, Sukanta Basu

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)

Abstract

In this study, a newly developed direct numerical simulation (DNS) solver is utilized for the simulations of numerous stably stratified open-channel flows with bulk Reynolds number (Reb) spanning 3400–16,900. Overall, the simulated bulk Richardson number (Rib) ranges from 0.08 (weakly stable) to 0.49 (very stable). Thus, both continuously turbulent and (globally) intermittently turbulent cases are represented in the DNS database. Using this comprehensive database, various flux-based and gradient-based similarity relationships for energy dissipation rate (ε) and temperature structure parameter ((Formula presented.)) are developed. Interestingly, these relationships exhibit only minor dependency on Reb. In order to further probe into this Reb-effect, similarity relationships are also estimated from a large-eddy simulation (LES) run of an idealized atmospheric boundary layer (very high Reb) case study. Despite the fundamental differences in the estimation of ε and (Formula presented.) from the DNS- and the LES-generated data, the resulting similarity relationships, especially the gradient-based ones, from these numerical approaches are found to be remarkably similar. More importantly, these simulated relationships are also comparable, at least qualitatively, to the traditional observational data-based ones. Since these simulated similarity relationships do not require Taylor’s hypothesis and do not suffer from mesoscale disturbances and/or measurement noise, they have the potential to complement the existing similarity relationships.

Original languageEnglish
Pages (from-to)373-399
Number of pages27
JournalEnvironmental Fluid Mechanics
Volume16
Issue number2
DOIs
Publication statusPublished - 1 Apr 2016
Externally publishedYes

Keywords

  • Direct numerical simulation
  • Energy dissipation rate
  • Large-eddy simulation
  • Similarity theory
  • Stable boundary layer
  • Temperature structure parameter

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