On the unsteady wake flow behind a sphere with large transverse-rotating speeds
Bibliographic record
Abstract
The unsteady wake downstream of a spinning sphere with a Reynolds number of 7930 (Re=UoD/ν, based on the sphere diameter and the free-stream velocity) and a range of spinning ratios (the ratio between the surface velocity and free-stream velocity, α=Vs/Uo) from 0 to 6.0 were studied using time-resolved particle image velocimetry. The Reynolds stresses and proper orthogonal decomposition results indicated that the wake exhibited distinct features in different spinning ratio regimes, and the state of the boundary layer played an important role in forming these features. In regime I (α≤0.25) where the boundary layer around the sphere was laminar, a pair of counter-rotating vortices emerged in the wake with unsteady size and position. The bottom boundary layer transitioned from laminar to turbulent as α increased from 0.25 to 0.75 (regime II). The transition caused a significant increase in the stream-wise stress as the unsteadiness becomes more coherent. The sphere was gradually covered by the turbulent boundary layer as α increased in regimes III and IV (0.75<α≤3.0). A large separation bubble was created in cases with α>3.0 (regime V); flow structures with a large stream-wise momentum separated from the bubble and was shed downstream with a strong flapping motion in the vertical direction, leading to large vertical stress behind the sphere.
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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 | 0.000 |
| 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 | 0.000 | 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".