Abstract
A DNS of a three dimensional diffuser has been performed with the in-house solver Alya. The resulting dataset presents a good agreement with existing numerical and experimental data, even without smoothing of the sharp corners. Discrepancies in the duct area have been found to be due to uncertainties, however, in the diffuser region differences are more noticeably between experimental and numerical data, where they all exhibit an oscillating behavior. The POD analysis of this flow has quantified a slow mixing mechanism inside the diffuser with a period of 4 flow-through times. This is due to the slow motions in the diffuser that are only represented 3 times over the 21 flow-through times in which statistics are gathered. This is considered to be the main reason of discrepancy between all datasets. While DNS of turbulent flow at \(Re=10,000\) are feasible nowadays, temporal dynamics of the Standford diffuser present a challenge as the integration time needed becomes larger. The current dataset is, nevertheless, valid for further analysis and activities and will be made available online.
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Acknowledgements
This work was funded as part of the European Project HiFi-TURB which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 814837.
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Miró, A., Eiximeno, B., Rodríguez, I., Lehmkuhl, O. (2024). DNS and POD Analysis of Separated Flow in a Three-Dimensional Diffuser. In: Marchioli, C., Salvetti, M.V., Garcia-Villalba, M., Schlatter, P. (eds) Direct and Large Eddy Simulation XIII. DLES 2023. ERCOFTAC Series, vol 31. Springer, Cham. https://doi.org/10.1007/978-3-031-47028-8_5
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DOI: https://doi.org/10.1007/978-3-031-47028-8_5
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