Coupling active and passive techniques to control the flow past the square back Ahmed body

Bruneau, Charles‐Henri; Creusé, Emmanuel; Depeyras, Delphine; Gilliéron, Patrick; Mortazavi, Iraj

doi:10.1016/j.compfluid.2010.06.019

Cited by 66 publications

(41 citation statements)

References 24 publications

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“…This yields an increase of the magnitude of the velocity tangent to the base, which results in a reduction of the static pressure acting in the same region. When the vortical structures are squeezed towards the base, as in the case of the plane located at y * = 0.34, this relation becomes even stronger, in agreement with the results of the numerical simulations performed by Bruneau et al (2010).…”

Section: Contribution Of the Base Wall Velocity To The Dragsupporting

confidence: 88%

Influence of short rear end tapers on the wake of a simplified square-back vehicle: wake topology and rear drag

2016

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As vehicle manufacturers work to reduce energy consumption of all types of vehicles, external vehicle aerodynamics has become increasingly important. Whilst production vehicle shape optimisation methods are well developed, the need to make further advances requires deeper understanding of the highly three-dimensional flow around bluff bodies. In this paper, the wake flow of a generic bluff body, the Windsor body, based on a square-back car geometry, was investigated by means of balance measurements, surface pressure measurements and 2D particle image velocimetry planes. Changes in the wake topology are triggered by the application of short tapers (4 % of the model length) to the top and bottom edges of the base, representing a shape optimisation that is realistic for many modern production vehicles. The base drag is calculated and correlated with the aerodynamic drag data. The results not only show the effectiveness of such small devices in modifying the time average topology of the wake but also shed some light on the effects produced by different levels of upwash and downwash on the bi-stable nature of the wake itself.

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Section: Contribution Of the Base Wall Velocity To The Dragsupporting

confidence: 88%

Influence of short rear end tapers on the wake of a simplified square-back vehicle: wake topology and rear drag

2016

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“…The quantitative results reported in Table are also highlighted in Figures and , respectively, depicting the mean velocity and mean vorticity fields. As already emphasized in the literature , the main source of drag forces for bluff bodies with square back is the low‐pressure recirculation zone in the near wake of the vertical wall. With λ = 1, the near‐wake structures are smaller, and the back recirculation zone is drastically reduced (Figure ).…”

Section: Extension To Solid–porous–fluid Media and Flow Controlmentioning

confidence: 88%

“…This provides a good motivation to perform flow control past such obstacles. Moreover, as it was shown in [49,50], a flow past a square back obstacle is not dominated by longitudinal vortical structures, therefore, a preliminary 2D study can be useful to supply information on general trends for a control.…”

Section: Modeling and Numerical Setupmentioning

confidence: 95%

Vortex penalization method for bluff body flows

Mimeau

Gallizio

Cottet

et al. 2015

Numerical Methods in Fluids

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International audienceIn this work, a penalization method is discussed in the context of vortex methods for incompressible flowsaround complex geometries. In particular, we illustrate the method in two cases: the flow around a rotatingblade for Reynolds numbers 1000 and 10,000 and the flow past a semi-circular body consisting of a porouslayer surrounding a rigid body at Reynolds numbers 550 and 3000. In the latter example, the results areinterpreted in terms of control strategy

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“…Much work has been devoted to the 25 • slant angle configuration; significant drag reductions are achieved through passive or active control strategies such as splitter plates [3], flaps [4,5], boundary layer streaks [6] or even pulsed jets [7]. Diverse strategies equally provide interesting base pressure recovery in the square-back case: splitter plates [8], porous devices [9] or active control [10].…”

Section: Introductionmentioning

confidence: 99%

Effect on drag of the flow orientation at the base separation of a simplified blunt road vehicle

et al. 2013

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Effect on drag of the flow orientation at the base separation of a simplified blunt road vehicle. Abstract The separated flow past the square-back model used in the experiments of Ahmed et al. [1] is controlled using flaps at the end of the top and bottom faces. A parametric study of the flow regarding the slant angle of the flaps is performed from pressure and force measurements as well as particle image velocimetry (PIV). When the bottom flap orientation is fixed, variations of the top slant angle evidence a drag versus lift quadratic dependence. This relationship presents self similarities changing the bottom flap angle.It is then observed that the lift is an affine function of both slant angles and the force a second order polynomial containing a coupling term between the two angles. These drag evolutions varying both angles are discussed and interpreted as contributions of the wake size, a drag induced by the lift and a local drag induced by the inclination of the flaps.

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Coupling active and passive techniques to control the flow past the square back Ahmed body

Cited by 66 publications

References 24 publications

Influence of short rear end tapers on the wake of a simplified square-back vehicle: wake topology and rear drag

Influence of short rear end tapers on the wake of a simplified square-back vehicle: wake topology and rear drag

Vortex penalization method for bluff body flows

Effect on drag of the flow orientation at the base separation of a simplified blunt road vehicle

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