Curved Riblet Tips for Drag Reduction in Water Pipes
Bibliographic record
Abstract
This study examines the role of riblet tip curvature in controlling drag in pipe flow and identifies how subtle geometric variations can alter performance.Three tip shapes were investigated: conventional flat tips, concave tips and convex tips.The riblets were manufactured using masked stereolithography 3D printing and systematically tested across a broad range of Reynolds numbers.The results show that tip curvature shows little influence under laminar conditions (Re < 2200), but becomes decisive once the flow enters transitional and turbulent regimes (Re > 2200).Convex tips consistently produced weaker drag reduction than flat tips, indicating that outward curvature may disrupt near-wall vortex organization.In contrast, concave tips enhanced drag reduction, yielding up to 30 percent drag reduction at Re ≈ 6000.However, the benefit diminished at both lower and higher Re, indicating strong sensitivity to flow-scale interactions.These findings demonstrate that riblet effectiveness is dependent on tip curvature and flow regime, and they provide new design principles for engineering advanced riblet surfaces that can reduce frictional losses and energy consumption in pipelines.
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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".