Some observations concerning "laminarization" in heated vertical tubes
Journal Article
·
· International Journal of Heat and Mass Transfer
- Idaho National Lab. (INL), Idaho Falls, ID (United States); Univ. of Idaho, Idaho Falls, ID (United States); Univ. of Stuttgart (Germany)
- Univ. of Stuttgart (Germany)
- Seoul National Univ. (Korea, Republic of)
For low "turbulent" Reynolds numbers in strongly-heated vertical gas flow, fundamental results of existing direct numerical simulation (DNS) databases have been examined to deduce differences between cases which "revert" to turbulent and those that yield integral parameters which correspond to laminar flow (henceforth laminarizing or laminarized). The objectives of this paper are (1) to examine the streamwise evolution of near-wall flow structures and (2) to determine which, if any, proposed laminarization parameters could be used to discriminate between turbulent and laminarizing flows resulting. Views of streamlines in r-θ cross sections showed evidence of a ring of irregular-shaped streamwise vortices near the wall at all locations. The transverse advection of these vortices is hypothesized to provide a path of least resistance to the transport of streamwise momentum in the wall-normal direction. It is demonstrated that a steady streamwise laminar vortex can provide apparent turbulent momentum transport (as a consequence of the Reynolds decomposition) such that a reasonable mean velocity profile is predicted near the wall. For the present cases, the values of the non-dimensional radius (yc,w+ = Reτ,w) and of the modified wall Reynolds number did discriminate whether turbulent or laminarizing flow resulted.
- Research Organization:
- Idaho National Laboratory (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- Grant/Contract Number:
- AC07-05ID14517; NE0008412
- OSTI ID:
- 1700498
- Report Number(s):
- INL/JOU--19-54399-Rev000
- Journal Information:
- International Journal of Heat and Mass Transfer, Journal Name: International Journal of Heat and Mass Transfer Journal Issue: - Vol. 163; ISSN 0017-9310
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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