Numerical Simulation Of Contrail Ice Particle Growth In The Near Field Of An Aircraft Engine
Bibliographic record
Abstract
Contrails from aircraft may have a direct impact on the Earth’s radiative budget balance. The aim of this study is to examine the formation of contrails in the near field of a realistic configuration based on the CFM56 engine and consequently, on the soot and ice particles evolution. In this work, we focused on a primary exhaust jet laden with soot particles and mixed with a secondary jet (bypass flow) in the cold ambient air. The study has been performed using a 2D axisymmetric CFD calculation based on an URANS (Unsteady Reynolds Average Navier-Stokes) approach. Numerical simulations have been performed using STAR-CCM+, a commercial code for multiphysics. The particles are tracked using the Lagrangian approach. A microphysical model was used to calculate their growth. The results show the evolution of ice crystal sizes throughout the exhaust jets. As an example, the mean particle radius grows up to approximately 0.7 μm 0.5 s downstream in agreement with experimental data.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".