Contrails formed by aircraft exhaust contribute significantly to global warming by altering the atmospheric radiative balance. Generated through the condensation of water vapor in the engine plumes, these artificial cloud structures can persist and trap infrared radiation, highlighting the need to understand their formation and evolution mechanisms. This thesis therefore aims to quantify the impact of dynamic and microphysical processes on the genesis and dispersion of these ice‐crystal clouds. A more accurate representation of these phenomena is essential for developing strategies to mitigate the climate impact of air traffic.
To this end, a numerical simulation approach based on Large Eddy Simulation (LES) was implemented using the CFD code Fludiles. Two microphysical models were compared: one assuming progressive particle activation before growth, and the other treating particles as immediately ready to condense. Simulations examined an isolated turbulent jet in temporal frameworks, followed by the interaction between the jet and a wake vortex in a temporal regime. Initial turbulence intensity and particle number density were varied to assess their influence on saturation fraction and particle growth.
Results show that the progressive‐activation model is highly sensitive to turbulence amplitude, which limits particle activation, whereas the direct‐activation model consistently achieves higher saturation levels. Introducing the wake vortex homogenizes growth, reducing competition for water vapor and neutralizing differences due to turbulence and density. This study underscores the crucial role of microphysics and the structuring influence of waking vortices in contrail modeling, paving the way for more reliable climate impact forecasts.
| Date | 2 Sept 2025 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | François Garnier (Supervisor) |
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Delanchy, A. (Author),
Garnier (Supervisor),
2 Sept 2025Student thesis: Master's thesis › Master in Engineering: Mechanical Engineering