Vortex dynamics of tandem bare and spiral finned cylinders in cross-flow and their susceptibility to acoustic resonance excitation
Bibliographic record
Abstract
The vortex dynamics of tandem bare and spiral finned cylinders in the cross flow are experimentally investigated at a spacing ratio of L/Deq=2. Three different fin pitch-to-root diameter ratios (p/Dr) are considered. For high p/Dr, the fins on the downstream cylinder inhibit the shear layer growth and flapping in the cylinders' gap. Shear layer flapping is only observed for finned cylinders with the lowest p/Dr. Moreover, the gap shear layers enclose the downstream cylinder, enabling the formation of large vortex cores. The flow characteristics of finned cylinders are found to be independent of the Reynolds number with higher values of the Strouhal number due to an enlarged vortex formation length. For tandem bare cylinders, acoustic resonance excitation is triggered by two sources: (1) shear layer flapping in the cylinders' gap and (2) vortex shedding in the wake of the cylinders. All the tandem finned cylinders were able to excite acoustic resonance by the latter source. However, only tandem finned cylinders with the lowest p/Dr were capable of exciting resonance by the former source. During this excitation, weaker shear layer flapping resulted in the formation of smaller vortex cores in the finned cylinders' gap. During the second resonance, single vortex pairs formed per cycle in the wake of the downstream finned cylinder, whereas two vortex pairs formed per cycle in the wake of the downstream bare cylinder. This work shows that the addition of fins changes the impinging flow mechanism and the flow topology, which cannot be captured using the equivalent diameter approach.
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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 | 0.000 | 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) | 0.000 | 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".