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The Ahmed Model Unsteady Wake: Experimental and Computational Analyses
Technical Paper
2003-01-1315
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
The unsteady wake of the Ahmed model has been investigated experimentally using time-accurate 5-hole and hot-wire probes and computationally using Exa PowerFLOW. The backlight angle was 25° which was chosen to be slightly below the critical angle observed computationally. The CFD results are similar to experimental results for backlight angles just below the critical angle (eg: 27.5°, 30°). Unsteady flow-field reconstruction of the experimental results and the CFD results both revealed a quasi-two-dimensional vortex-shedding type structure from the bottom of the model base. This results in a semi-periodic build up and collapse of the near wake and produces a symmetric oscillation in the strength and position of the rear pillar vortices. The period of this phenomenon corresponds to a Strouhal number of approximately 0.5 based on free-stream velocity and the square root of the model frontal area.
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Citation
Sims-Williams, D. and Duncan, B., "The Ahmed Model Unsteady Wake: Experimental and Computational Analyses," SAE Technical Paper 2003-01-1315, 2003, https://doi.org/10.4271/2003-01-1315.Also In
SAE 2003 Transactions Journal of Passenger Cars - Mechanical Systems
Number: V112-6; Published: 2004-09-15
Number: V112-6; Published: 2004-09-15
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