Spatial large eddy simulation of contrail formation in a near field of anaircraft engine : comparative study of different ambient humidity
Bibliographic record
Abstract
The study of aircraft contrails involves several physical and chemical processes at various spatial and temporal scales, from contrail formation near the engine exhaust up to contrail cirrus at a large scale depending on the atmospheric conditions.Given the impact of near field jet characteristics on the contrail life cycle, characterizing the dynamic and microphysical properties of jet contrails has been emphasized.Within the large eddy simulation (LES) framework, the modeling of contrail formation in literature is mostly performed using a temporal approach by assuming axial gradients negligible as compared to radial ones, which is only valid far from the engine nozzle.In contrast, the spatial LES approach is more rigorous and allows for modeling the entire jet development with no assumptions.Moreover, based on the changing concentrations of water vapor in the upper troposphere, and the difficulties in measuring that, modeling the aircraft engine in different levels of relative humidity in the atmosphere is crucial.As such, we propose to use a spatial LES to better characterize the dynamic and microphysical properties in the near field of an aircraft exhaust at cruise level for two cases in different ambient conditions in terms of relative humidity value.A high-order (six orders in space and three orders in time) compressible computational fluid dynamic (CFD) code, FludiLES, was used along with an ice-only microphysical model to investigate contrail particles in an Eulerian-Lagrangian approach.Model validation of 1 st and 2 nd order statistics of turbulence with experimental results showed a good agreement in the case of a round jet.Furthermore, contrail microphysical properties (saturation ratio, particle radius, and optical depth) were characterized in the case of the CFM56-3 engine.The analysis of results at two ambient relative humidity 60% and 130% confirmed literature findings; the case of saturated ambient conditions leads to larger ice particles and with plume age, fewer particles are evaporated as compared to the lower relative humidity case.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".