Effect of Reynolds number, near-wall perturbation and turbulence on smooth open-channel flows
Bibliographic record
Abstract
Abstract Three series of experiments were conducted to study the effect of Reynolds number, near-wall perturbation and turbulence on the velocity characteristics of smooth open-channel flows. Measurements were carried out using a laser Doppler anemometer. The variables of interest include mean velocity, turbulence, velocity probability density functions and Gram-Charlier series coefficients. For the range of depth Reynolds number studied (23×103 < Re h <72×103), the turbulence intensity and Reynolds shear stress profiles show that the effect of Reynolds number can be significant in open-channel flows. However, at identical distances from the bed, the velocity probability density functions are relatively insensitive to Reynolds number effects. The coefficients of the Gram-Charlier series expansion are also independent of Reynolds number for wall normal distances y+ <300. In the case of the flow with the near-wall perturbation, the mean velocity profile at the farthest downstream station more-or-less recovers to the undisturbed state, whereas the turbulence intensity profiles do not completely recover. From the various profiles obtained downstream of the perturbation, the wall-normal distance corresponding to 0.01<y/h<0.1 requires a greater longitudinal distance to recover to the undisturbed state. As noticed from the velocity defect profiles, the effects of near-wall disturbance begin to penetrate into the flow with increasing distance from the perturbation. The presence of higher levels of turbulence influences the skin friction coefficient, the extent of collapse with the log–law and the wake parameter. Keywords: Open-channel flownear-wall perturbationfree stream turbulenceprobability density functionsReynolds shear stressskin friction coefficientflow recovery
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.000 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".