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Influence des conditions amont sur l'écoulement derrière une marche par la Simulation des Grandes Echelles

Abstract : In this study, Large Eddy Simulations of the flow over a backward-facing-step are used to investigate the influence of upstream boundary conditions on the development of turbulent structures.
The first inlet condition consists of a mean turbulent profile perturbed by white-noise. This condition is compared to a second, more realistic one, in which fully turbulent inflow data is derived from an auxiliary simulation of a quasi-temporal boundary layer. Velocity and pressure statistics, supplemented by flow visualizations demonstrate how the flow in the separated shear layer is modified by the inlet condition.
In the case where the inlet stemmed from a precursor simulation, it was found that the incoming turbulent structures significantly influence the flow development downstream of the step expansion. In particular, it is shown how the streaks and the quasi-streamwise vortices trigger a rapid destabilization of the shear layer which results in a shortening of the reattachment length.
The flowfields of both simulations evolve in such a way that their structure is relatively similar in the vicinity of the reattachment zone. Beyond this region this inlet condition has a negligible influence over the flow.
Analysis of the temporal spectra of the flowfield showed two regimes of low oscillations inherent to this type of configuration, namely, the oscillation of the mean reattachment and the flapping of the detached shear-layer. Finally, modification of the interaction between the shear layer and the recirculation bubble is proposed to explain the increase in low-frequency unsteadiness.
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https://tel.archives-ouvertes.fr/tel-00410462
Contributor : Alexandra Danet <>
Submitted on : Thursday, August 20, 2009 - 5:26:18 PM
Last modification on : Thursday, July 23, 2020 - 3:00:48 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 8:03:26 PM

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  • HAL Id : tel-00410462, version 1

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Alexandra Danet. Influence des conditions amont sur l'écoulement derrière une marche par la Simulation des Grandes Echelles. domain_other. Institut National Polytechnique de Grenoble - INPG, 2001. Français. ⟨tel-00410462⟩

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