Air–water interaction in a partially filled circular pipe
Bibliographic record
Abstract
This study investigates the combined effects of water drag forces and air pressure gradients on air movement within the headspace of a circular pipe. Under free ventilation conditions, where air enters the system solely through natural suction induced by water flow, positive pressure gradients were observed. The air pressure gradients increased with both the filling ratio and water flow rate. It was also found that air near the water surface flowed downstream due to water drag force, while air near the pipe crown moved upstream. Forced ventilation was introduced through air extractors positioned at the upstream and downstream vents, with adjustable power to create varying airflow rates. Results showed that beyond certain thresholds, increased air extractor power did not further enhance ventilation. Under forced ventilation, air velocity profiles in the non-boundary zone exhibited a more uniform distribution due to higher ventilation power. The effects of water drag, air pressure gradients, and pipe wall friction were analyzed. The critical pressure gradients with negligible water drag under forced ventilation were obtained. The drag coefficients of water on the airflow were calculated, ranging from 0.018 to 0.081 for free ventilation and from 0.002 to 0.038 for forced ventilation. A semi-empirical equation for calculating the drag coefficients under free ventilation was proposed. This study provides valuable insight into the dynamics of air movement in sewer systems, emphasizing the critical role of proper ventilation design in mitigating odor and corrosion issues.
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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 | 0.001 |
| 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".