CFD Based Analysis of Multiphase Flows in Bends of Large Diameter Pipelines
Bibliographic record
Abstract
Abstract This paper describes a computational fluid dynamics (CFD) analysis performed to predict the characteristics of the dominant multiphase flow regime in over-bends and under-bends of a typical large-diameter heavy crude oil pipeline. It was noticed in field indirect inspections and also studied in the literature that pipelines downstream of the over-bends are usually prone to localized pitting corrosion but the root-cause of this phenomenon is not fully understood and therefore further investigation is still required. In this study the effect of crude API density, water to oil flow-rate ratio (water-cut) as well as pipeline internal diameter, inclination angle and total flow rate on the water-wetted surface area for a stratified multi-phase flow regime is investigated using a 3D numerical simulation technique. The water-oil interface inside the pipeline and the effect of the pipeline inclination angle on the shape of this interface for different sets of operational conditions is studied. The paper shows that the secondary flow, the Dean flow, due to a change of orientation of the pipe spreads the water on the wall of the pipe for a positive slope and accumulates the water in the center for a negative slope.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".