Modulation of transient pressure by an air pocket in a horizontal pipe with an end orifice
Bibliographic record
Abstract
In urban drainage systems, a sudden increase in the flow rate can cause the transition of the flow from open channel to pipe flow, and the entrapment of large air pockets in sewers, which might result in serious geysers and water-hammer like pressure events. This paper presents a numerical analysis of flow processes associated with the pressurization and release of an air pocket in order to study its influence on transient pressure in a horizontal pipe with an end orifice. The influence of the air pocket inside the pipe on the peak pressure can be described in two distinct regimes. In regime I for the pipe with a small orifice, the peak pressure is modulated by the pressurization and expansion of the air pocket and its subsequent damping. In regime II for the pipe with a large orifice, air can be quickly expelled, and the water column directly impinges on the pipe end wall and causes water-hammer like pressure. With the increase of the orifice size, the peak pressure decreases due to the change in the water velocity. In the study cases, the peak pressure in regime I is about two times the inlet pressure, while it can be more than forty times in regime II.
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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 | 0.000 |
| 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".