The Effect of End Conditions on Laminar and Turbulent Natural Convective Flow in a High Aspect Ratio Enclosure
Bibliographic record
Abstract
The transition from laminar to turbulent natural convective flow in tall, i.e., high aspect ratio, rectangular enclosures with isothermal vertical walls has been numerically studied. The flow in the enclosure has been assumed to be steady and fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces, this being dealt with by adopting the Boussinesq approach. The solution has the Rayleigh number, the Prandtl number, the Aspect Ratio of the enclosure (height-towidth ratio), and the conditions existing at the top and bottom of the enclosure as parameters. Results have only been obtained for a Prandtl number of 0.7. Aspect ratios of between 10 and 20 and Rayleigh numbers based on enclosure height of between 10 5 and 10 12 have been considered. Two different types of end conditions at the top and bottom of the enclosure have been considered these being that the top and bottom are adiabatic or that the top and bottom are made from a conducting material. In this latter case the ratio of the thermal conductivity of the end material to the thermal conductivity of air is also a parameter on which the solution depends. Results have been obtained using a standard kepsilon turbulence model that fully accounts for buoyancy force effects. The solutions have been obtained using the commercial cfd solver FLUENT. The main purpose of the study was to determine whether the conditions at the top and bottom of the enclosure affect the mean heat transfer rate across the enclosure or the local heat transfer rate distributions along the heated and cooled vertical walls or the conditions under which turbulence effects become important.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".