On the sources of jet noise: a numerical study using band-pass Filtering
Bibliographic record
Abstract
Bandpass filtering of the flow and sound was performed in order to gain further insight into the role of coherent structures in subsonic jet noise generation. The bandpass filtering procedure was conducted on the data obtained from a well-resolved large eddy simulation of sound radiation from an unheated, Mach 0.9 jet at ReD = 400,000. Results from the bandpass filtering of the pressure field suggest two dominant mechanisms of sound radiation in unheated subsonic jets that can occur in all scales of turbulence. The first mechanism is the stretching and the distortion of coherent vortical structures. For large scale structures, i.e. low frequency radiation, this mechanism is dominant close to the termination of the potential core. This mechanism appears quadrupolar in nature, and is responsible for strong sound radiation at aft angles. The second sound generation mechanism appears to be the transverse vibration of the shear-layer interface within the ambient quiescent flow. This mechanism is believed to be responsible for sound radiation along the sideline directions.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".