Experimental Investigation of the Aeroacoustic Sources in a Tandem Cylinder Configuration
Bibliographic record
Abstract
The empirical investigation of the spatial distribution of resonant acoustic sources around a tandem cylinder configuration subject to cross flow in a duct and an imposed transverse acoustic wave is described. The imposed wave induced acoustic “lock-in” and the vortex shedding frequency from the cylinders became entrained to the frequency of the imposed wave near acoustic-Strouhal coincidence. Howe’s aeroacoustic theory was used to couple an acoustic field to a hydrodynamic flow field and the spatial distribution of the time-resolved acoustic power and net-acoustic energy throughout a complete acoustic wave cycle at two resonant conditions were calculated. The first resonant condition occurred at a low flow velocity before acoustic-Strouhal coincidence, whilst the second occurred at a higher flow velocity just after acoustic-Strouhal coincidence. The acoustic field was analysed using finite element analysis combined with microphone pressure measurements whilst the hydrodynamic flow field was extracted using particle image velocimetry from a field of view concentrated around the cylinders and roughly three diameters downstream of them. For both resonant conditions, the dominant individual sources were found to lie in the shear layers of the gap region between the cylinders, however, stronger individual sinks were found to be located there also. Thus, for the amplitude of the applied sound wave and for the available field of view, the gap shear layer region contributed an overall acoustic sink whilst the wake contributed an overall acoustic source.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".