The measurement of wake and surface effects in the subcritical flow past a circular cylinder at rest and in vortex-excited oscillation
Bibliographic record
Abstract
A pressure transducer, sensitive to acoustic level pressures, was designed and used to measure amplitude, frequency and phase of fluctuating pressure on the surface of a three inch diameter circular cylinder at rest and exhibiting large-amplitude vortex-excited oscillation in a uniform incident wind flow. The phase of the fluctuating pressure relative to the cylinder motion and the cylinder amplitude and frequency were recorded. A disc probe connected to the pressure transducer was used in wake surveys for the stationary and oscillating cylinder. Measurements, made in the Reynolds number range 1.5(10⁴) <N(R)< 4.1(10⁴), indicated the following: Fluctuating pressures on the surface of both a stationary and a vortex-excited circular cylinder experience amplitude modulation, being random for the stationary cylinder and critically dependent on wind speed for the vortex-excited cylinder. Fluctuating pressures for both a stationary and an oscillating cylinder are in phase over one side of the cylinder and 180° out of phase with the opposite side. For a vortex-excited cylinder, the vortex frequency is 'captured' by the cylinder frequency over a discrete range of wind speed. The amplitude of fluctuating pressure on the surface of a vortex-excited cylinder increases as the resonant wind speed (wind speed corresponding to maximum cylinder amplitude) is approached, but before that actual wind speed is reached, an abrupt decrease occurs, and the amplitude modulation nearly disappears. A sudden change of phase between cylinder motion and fluctuating pressure occurs near the resonant wind speed and the pressure wave form becomes asymmetrical. The longitudinal spacing of vortices in the wake of a stationary and a vortex-excited cylinder initially increases as the vortices are swept downstream from the formation zone. Vortex-excited oscillation of a cylinder, as the resonant wind speed is approached, produces an increase in longitudinal vortex spacing and a corresponding abrupt decrease in lateral spacing. At the resonant wind speed, the wake loses its coherent periodicity.
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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 | 0.001 | 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) | 0.000 | 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 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".