Budgets of turbulent stresses and fluxes in a vertical slot natural convection flow at Rayleigh Ra = 105and 5.4 105
✍ Scribed by R. Boudjemadi; V. Maupu; D. Laurence; P. Le. Quéré
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 780 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0142-727X
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✦ Synopsis
A direct numerical simulation (DNS) of natural turbulent convection in a differentially heated infinite vertical slot has been computed with a mixed finite difference/Fourier code at Rayleigh numbers of Ra=l.0 105 and Ra=5.4 105 . A database containing up to second-order budgets has been collected, and the physics of the Reynolds stresses and turbulent heat fluxes is analyzed in light of the relevant conservation equations. Unusual features are the negative production terms and countergradient turbulent transport. Near-wall flow characteristics are strongly influenced by transport of quantities from the core of the "'Couette flow" where most of the turbulence is produced. A fairly simple second-moment closure, relying on elliptic relaxation instead of damping functions for near wall effects, is found to perform fairly well on a global scale. Although the modeling approach is open for improvements if a term-by-term analysis is conducted.