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Experiments in Fluids

, 59:124 | Cite as

Time-averaged three-dimensional flow topology in the wake of a simplified car model using volumetric PIV

  • Prabu Sellappan
  • Jonathan McNally
  • Farrukh S. Alvi
Research Article

Abstract

Fuel shortages and air pollution are two major incentives for improving the aerodynamics of vehicles. Reducing wake-induced aerodynamic drag, which is strongly dependent on flow topology, is important for improving fuel consumption rates which directly affect the environment. Therefore, a comprehensive understanding of the baseline flow topology is required to develop targeted drag reduction strategies. In this research, the near wake of a generic ground vehicle, a \(25^{\circ }\) slant Ahmed model at a flow Reynolds number of \(Re =1.1\times 10^{6}\), is investigated and its flow topology elucidated. The flow field of this canonical bluff body is extremely rich, with complex flow features such as spanwise trailing wake and streamwise C-pillar vortices. The flow is characterized through stereoscopic and tomographic velocity field measurements. The large-scale, horseshoe vortex structures in the trailing wake, conventionally denoted as A- and B-vortices, are found to vary in size and shape along the spanwise direction, which in turn influence the pressure distribution on the rear vertical surface. The longitudinal C-pillar vortices are found to extend far downstream and also influence the trailing wake structures through a complex, three-dimensional interaction. The accuracy and cost of obtaining volumetric information in this complex flow field, by means of volume reconstruction, through Stacked Stereoscopic-Particle Image Velocimetry (PIV) and Tomographic PIV are also investigated.

Notes

Acknowledgements

The authors would like to thank Jeremy Phillips, Adam Piotrowski, and Bobby Avant for their help with model fabrication. The research is supported in part by the National Science Foundation PIRE program and the Florida Center for Advanced Aero-Propulsion (FCAAP).

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Florida Center for Advanced Aero-Propulsion (FCAAP), FAMU-FSU College of EngineeringThe Florida State UniversityTallahasseeUSA

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