Hydraulic jumps influenced airflow in a partially filled circular pipe
Bibliographic record
Abstract
A hydraulic jump is one of the most common hydraulic features in open channel flow, inducing extra turbulence. The generation and release of hazardous gases, such as H2S and CH4, can be largely affected by the air movement induced by hydraulic jumps, posing corrosion and health risks in urban drainage systems. Despite extensive research on hydraulic jumps in open channels, gaps persist in understanding air–water interactions in partially filled circular pipes. This study experimentally examines the characteristics of hydraulic jumps and the associated air motion in a partially filled pipe. Experiments were performed in a 0.3 m diameter pipe, with water flow rates ranging from 8 to 21 l/s. Air flowrates and air pressure gradients along the pipe were measured to quantify relative air demand, drag coefficients, and momentum transfer. These results show that the relative air demand β, defined as a ratio of air to water flow rate, increases with the Froude number (Fr) of water flow, especially for Fr < 2, reaching 0.015–0.058 under partially filled conditions, substantially higher than that one for downstream full pipe flow cases. Across the hydraulic jump region, pressure gradients are 20%–80% greater than the ones at upstream or downstream sections, driven by rapid momentum flux changes and intensified turbulent dissipation. Drag forces and pressure gradients are identified as the dominant drivers of air motion, while wall friction is negligible. Drag coefficients decrease with increasing Fr. These findings improve the understanding of air–water interactions in partially filled circular pipes.
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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 | 0.001 |
| 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) | 0.001 | 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".