Flow Regime Transition and Air Entrapment in Combined Sewer Storage Tunnels
Bibliographic record
Abstract
The rapid filling of a stormwater storage tunnel is accompanied by a flow regime transition from free surface to pressurized flow with the presence of a hydraulic bore.Nearly all previous experimental investigations of flow regime transition have involved the study of pipe-filling bores; this seems to be a consequence of the experimental setup implemented as opposed to a necessarily common occurrence in prototype systems.In analyzing transient filling conditions in a large combined sewer overflow storage tunnel proposed for Washington DC, it became clear that the flow regime transition more commonly occurs as a gradual flow regime transition which involves a regular free surface bore followed by a gradually sloping free surface up to the pipe crown.This unsteady process can result in air pockets being trapped and pressurized in the system.As these air pockets reach a ventilation shaft, they can be quickly released upward in an air-water mixture.This phenomenon known as geysering potentially results in the untreated poor quality water returning to the surface.Laboratory experiments were used to observe the formation of pressurized air pockets and geysering events associated with gradual flow regime conditions.Geysers that occur due to the release of these air pockets do not necessarily correspond to high pressures in the system.The consequences of these observations for the requirements of numerical models are discussed.It is also
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".