Title: Aerodynamic characterisation of a square back bluff body flow

Authors: Arnaud Lahaye; Annie Leroy; Azeddine Kourta

Addresses: PRISME Laboratory, University of Orléans, 8 rue Léonard de Vinci, 45072 Orléans, France; French Environment and Energy Management Agency, 20 avenue du Grésillé – BP90406, 49004 Angers, France ' PRISME Laboratory, University of Orléans, 8 rue Léonard de Vinci, 45072 Orléans, France ' PRISME Laboratory, University of Orléans, 8 rue Léonard de Vinci, 45072 Orléans, France

Abstract: This article deals with the flow characterisation around a square back Ahmed body. Results of time-averaged and instantaneous flow characteristics are compared to the literature. All the results presented in this article were obtained when the Reynolds number independency of the drag coefficient was reached. The first part of the study focuses on time-averaged results. The turbulent boundary layer on the roof of the model has been characterised and mean flow topology is investigated thanks to particle imaging velocimetry and pressure measurements. The second part of the paper is dedicated to the characterisation of the vortex shedding in the wake using hot wire anemometry. The phase difference of vortex shedding between two edges, the vortex pairing in the shear layers and the pumping effect are tackled.

Keywords: automotive aerodynamics; Ahmed body; square back body; vortex shedding; bluff body wake; drag coefficient; turbulent boundary layers; vortex pairing; shear layers; pumping effect.

DOI: 10.1504/IJAD.2014.057804

International Journal of Aerodynamics, 2014 Vol.4 No.1/2, pp.43 - 60

Available online: 12 Jul 2013 *

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