Bibliographic record
Abstract
The effects of freestream turbulence intensity and integral length scale as freestream turbulent parameters on the drag coefficient of a solid sphere were experimentally investigated in a closed-circuit wind tunnel. The Reynolds number, Re = Ud/ν, was varied from 2.2×104 to 8×10 4 by using spheres of different sizes in addition to altering the freestream velocity, U. Two different kinds of spheres, PVC spheres with diameter d of 20, 51 and 102 mm and wooden spheres with diameter d of 20, 51, 65, 102, 140 and 210 mm, were used in Experiments I and II, respectively. The freestream turbulence intensity Tu and flow integral length scale Λ were manipulated by using orificed perforated plates. The proper combination of orificed perforated plate hole diameter, sphere size, and sphere location enabled the independent variations of turbulence intensity and relative integral length scale (Λ/d) from 1.8% to 10.7% and from 0.1 to 2.6, respectively at each studied Reynolds number in Experiment I, and in Experiment II, the independent variations of turbulence intensity and relative integral length scale (Λ/d) from 2.5% to 6.3% and from 0.04 to 3.3, respectively at each studied Reynolds number. To ease the experiment process, the sphere was fixed while the location of the orificed perforated plate was varied in Experiment II. Our 'smooth flow' (Tu < 0.3%) results agree with the standard CDversus Re results in the literature. Over the range of conditions studied, current results have confirmed that the drag always decreases with increasing Tu and the critical Reynolds number at which the drag coefficient is dramatically reduced is advanced with increasing Tu. It is found that the effectiveness of Tu in reducing CD is optimized when A is about 0.65d.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".