A comparative study of the turbulent flow field with and without a pebble cluster in a gravel bed river
Bibliographic record
Abstract
This paper investigates the processes and spatial patterns of the turbulent flow around a naturally formed in situ pebble cluster and the interactions with large‐scale coherent flow structures. Instantaneous high‐frequency velocities were measured using the simultaneous deployment of four acoustic Doppler velocimeters, with the pebble cluster and after the cluster was removed. Results indicate a twofold increase in turbulent kinetic energy over the sampling area when the pebble cluster is present. Individual vertical component velocity spectra in the wake of the pebble cluster contain a marked peak which decreases in frequency from 1.8 Hz near the cluster to 1.0 Hz farther downstream. This peak is associated with eddies shedding from the shear layer in the lee of the cluster, and it agrees well with the values estimated using a Strouhal number of 0.18. Space‐time correlations indicate the presence of coherent depth‐scale macroturbulent flow structures. These structures in the intermediate flow region are relatively unaffected by eddies shedding from the pebble cluster. The results suggest the effects of the pebble cluster on the surrounding flow dynamics are quite localized and limited to the near‐bed region.
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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 | 0.001 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".