Investigation of Pressure Drop and Heat Transfer Behavior of a Square Channel with 45° Angle Ribs at Wide Range of Reynolds Numbers
Bibliographic record
Abstract
An experimental investigation of the friction and heat transfer behavior for a fully developed flow in a square channel was conducted under a wide range of Reynolds numbers (Re) from 6,000 to 180,000. The test section was 22 hydraulic diameters (Dh) long, and made of four aluminum plates. The interior comprised of two opposing rib roughened walls and two opposing smooth walls. The ribs were oriented at 45° to the flow direction, and the ratio of rib height to channel hydraulic diameter (e/Dh) and the ratio of pitch to rib height (p/e) were 0.063 and 10, respectively. A 20Dh long acrylic channel with a continuation of the test section’s interior was attached at the inlet of the test section to confirm the flow to be fully developed. For the heat transfer tests, the four walls of the test section were maintained at isothermal conditions. The friction factor, the average Nusselt number (Nu), and thermal performance of the channel were compared with the available data in the existing literature in Re ranging from 6,000 to 70,000. An extensive investigation was performed at higher Re up to 180,000. The results show that the heat transfer augmentation (Nu/Nu0) caused by the ribs approaches a constant value around 2.0 after 8.0 Dh distance in the tested Re range. However, as Re increases, the friction factor enhancement (f/f0) also increases linearly, which gradually reduces the overall thermal performance. Comparative numerical studies have also been conducted by solving Reynolds Average Navier Stokes(RANS) equations by using v2-f turbulence model with all y+ wall treatment in the same range of Re as in experiment. It is found that v2-f turbulence model overpredicts both the experimental heat transfer and friction results.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".