Quality and reliability of LES of convective scalar transfer at high Reynolds numbers

Qi Li, Elie R. Bou-Zeid, William Anderson, Sue Grimmond, Marcus Nils Hultmark

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Numerical studies were performed to assess the quality and reliability of wall-modeled large eddy simulation (LES) for studying convective heat and mass transfer over bluff bodies at high Reynolds numbers (Re), with a focus on built structures in the atmospheric boundary layer. Detailed comparisons were made with both wind-tunnel experiments and field observations. The LES was shown to correctly capture the spatial patterns of the transfer coefficients around two-dimensional roughness ribs (with a discrepancy of about 20%) and the average Nusselt number (Nu) over a single wall mounted cube (with a discrepancy of about 25%) relative to wind tunnel measurements. However, the discrepancy in Re between the wind tunnel measurements and the real-world applications that the code aims to address influence the comparisons since Nu is a function of Re. Evaluations against field observations are therefore done to overcome this challenge; they reveal that, for applications in urban areas, the wind-tunnel studies result in a much lower range for the exponent m in the classic Nu ∼ Rem relations, compared to field measurements and LES (0.52–0.74 versus ≈ 0.9). The results underline the importance of conducting experimental or numerical studies for convective scalar transfer problems at a Re commensurate with the flow of interest, and support the use of wall-modeled LES as a technique for this problem that can already capture important aspects of the physics, although further development and testing are needed.

Original languageEnglish (US)
Pages (from-to)959-970
Number of pages12
JournalInternational Journal of Heat and Mass Transfer
Volume102
DOIs
StatePublished - Nov 1 2016

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

Keywords

  • Forced convective heat transfer
  • Large-eddy simulation
  • Rough walls
  • Urban heat exchange

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