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Simulation de l'écoulement atmosphérique au voisinage d'une tête de tunnel

Abstract : The design of a mechanical ventilation system in a tunnel requires to identify all the physical phenomena involved in the movement of the air in the tunnel. That is in order to establish the necessary ventilation capacities with regard to regulatory objectives. Atmospheric effects feature among the mechanisms likely to generate overpressures or depressions near the openings of a tunnel and consequently to induce or to modify the airflow established inside. This research work intends to contribute to a better understanding as well as a better consideration of the external atmospheric effects in tunnel ventilation studies.Experimental and numerical modeling have been completed. Wind tunnel tests were carried out in the atmospheric wind tunnel of the École Centrale de Lyon and used different techniques (PIV, hot wire anemometry, micromanometer) to measure the mean and turbulent statistics of the atmospheric flow in the vicinity of a tunnel. Time averaged (RANS) and filtered (LES) turbulence models were also used to simulate the atmospheric flow around a tunnel.The suitable representation of the unsteady turbulent atmospheric flow at the inlet of an LES computational domain remains an issue. During this work, we implemented a synthetic turbulence generator in the CFD code Fluent and, through comparison with experimental data, derived the optimal setup for the simulation of a fully rough atmospheric boundary layer.Thereafter, two tunnel configurations were studied by numerical and experimental means. In a first series of tests, the pressure field at the front section of a rectangular cavity was studied. The comparisons between the different approaches highlighted the influence of the geometry of the tunnel and the arrangement of the surrounding urban-like environment, as well as a better performance of the LES model in the description the turbulent flow. And in a second series of tests, we got closer to a realistic configuration and instrumented an open tunnel in which we could create an airflow directed towards the outside or the inside of the structure. The results showed a significant interaction between the atmospheric boundary layer and the three-dimensional wall jet from the tunnel.
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https://theses.hal.science/tel-03144552
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Submitted on : Wednesday, February 17, 2021 - 4:53:14 PM
Last modification on : Friday, September 30, 2022 - 10:56:10 AM
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  • HAL Id : tel-03144552, version 1

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Thierry Kubwimana. Simulation de l'écoulement atmosphérique au voisinage d'une tête de tunnel. Autre. Université de Lyon, 2020. Français. ⟨NNT : 2020LYSEC023⟩. ⟨tel-03144552⟩

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