On the oscillatory behavior of two pendulum-like tandem circular slender cylinders
Bibliographic record
Abstract
This experimental study investigates the flow–structure interaction of two identical tandem slender cylinders subjected to cross-flow in a wind tunnel. The upstream and downstream cylinders were mounted in a pendulum-like configuration, allowing only transverse oscillation with matching natural frequencies, and were also tested in a fixed configuration for comparison purposes. All experiments were performed at spacing ratios ranging from 2.0 to 7.5, within a Reynolds number range of 16,000 to 22,000. Lateral displacements were recorded using a high-speed camera, and flow structures were analyzed using Particle Image Velocimetry (PIV). The primary objective was to correlate the observed flow dynamics from the PIV results with the oscillatory behavior of the cylinders. The results show that oscillations occurred for all investigated spacing ratios, with the most significant oscillations observed at a spacing ratio of 2.0 and a distinctive pattern with extreme amplitudes at a spacing ratio of 3.5. Cross-correlation of the Discrete Wavelet Transform of the vibration response reveals that the vibration of the downstream cylinder are influenced by the wake of the upstream cylinder, with its amplitude remaining enveloped within the wake of the upstream cylinder. The flow structure driving the oscillatory behavior indicates that the vibrations of the cylinders are predominantly governed by wake-induced vibration, except for the case of L / D = 3 . 5 , where a galloping-like instability was observed—a mechanism not previously reported for this configuration. The phenomenon described in this paper presents potential opportunity for energy harvesting applications.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".