Boat-tail effects on the global wake dynamics of a flat-backed body with rectangular section

Bonnavion, Guillaume; Cadot, Olivier

doi:10.1016/j.jfluidstructs.2019.01.009

Cited by 19 publications

(4 citation statements)

References 21 publications

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“…The location of these perturbations varies from upstream of the base of the geometry (inflow conditions (Kang et al. 2021), asymmetric boat-tailing/tapering (Bonnavion & Cadot 2019; Pavia, Passmore & Varney 2019), yaw (Cadot, Evrard & Pastur 2015; Li et al. 2019) or pitch (Bonnavion & Cadot 2018)) to the base of the geometry (pulsed jets (Li et al.…”

Section: Introductionmentioning

confidence: 99%

“…The orientation of asymmetry related to the instability can be selected by various types of asymmetric perturbations. The location of these perturbations varies from upstream of the base of the geometry (inflow conditions (Kang et al 2021), asymmetric boat-tailing/tapering (Bonnavion & Cadot 2019;Pavia, Passmore & Varney 2019), yaw (Cadot, Evrard & Pastur 2015;Li et al 2019) or pitch (Bonnavion & Cadot 2018)) to the base of the geometry (pulsed jets (Li et al 2016), active flaps (Brackston et al 2016)). An important subset of asymmetric perturbations is located between the underside and the ground, for example ground clearance (Grandemange, Gohlke & Cadot 2013a), the ratio of the underbody velocity to free-stream velocity (Castelain et al 2018) and underbody roughness (Perry & Passmore 2013).…”

Section: Introductionmentioning

confidence: 99%

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Near wake interactions and drag increase regimes for a square-back bluff body

et al. 2022

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The three-dimensional near wake of a square-back bluff body in ground proximity is experimentally perturbed by placing a pair of D-shaped obstacles under the body. Five obstacle widths $d$ , from 12 % to 26 % of the height of the body, are used to perform a sensitivity study of the body's pressure drag by varying the relative distance $l$ between the obstacle pair and the base. Two successive drag-sensitive regimes are identified for obstacle-to-base distances $l/d < 2.5$ , where the pressure drag of the body is increased up to 22 %. In different regimes, the flow dynamics measured downstream of the obstacles are found to be very different. When the obstacles are the closest to the base, $l/d<1.5$ , the pressure drag changes of the main body are driven by mean merging between the wakes of the obstacles and of the main body, and scale with $d$ . Contrarily, when the obstacles are located farther from the base, $1.5< l/d<2.5$ , the wakes of the obstacles are isolated from the main body wake. Here the dynamics of the obstacle wake drive the pressure drag changes of the main body, which scale with $d^{2}$ . In both regimes, we measure a mean mass transfer from the wake of the main body to the wakes of the obstacles. This is the main mechanism responsible for the pressure drag changes. Using our results and reference studies describing the effects of base suction on the pressure drag of bluff bodies, a physical model is proposed to explain the contrasting scalings of the pressure drag increase in the different regimes observed in this study.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Near wake interactions and drag increase regimes for a square-back bluff body

et al. 2022

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“…In addition to jet actuation, there have been several investigations to control the static mode either passively with steady disturbances placed around the body (Grandemange, Gohlke & Cadot 2014;Cadot, Evrard & Pastur 2015;Barros et al 2017), with a base cavity (Evrard et al 2016;Lucas et al 2017;Bonnavion & Cadot 2018), with base boat-tailing (Perry, Passmore & Finney 2015;Pavia, Passmore & Gaylard 2016;Bonnavion & Cadot 2019) or actively with flaps (Brackston et al 2016; García de la Cruz, Brackston & Morrison 2017;Brackston, Wynn & Morrison 2018). Overall, three main effects have been observed.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of the effect of local base blowing on three-dimensional wake modes

Lorite-Díez

Jiménez-González

Pastur³

et al. 2019

J. Fluid Mech.

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“…A popular passive technique is the so-called boat-tailing, which consists of large geometrical modification of the base of the body leading to a gradual reduction of the bluff body's cross-section. This passive technique has been successfully applied to reduce the pressure drag of various types of bluff blunt bodies like two-dimensional bodies (Maull & Hoole 1967), axisymmetric bodies (Mair 1969) or square-section bodies (Wong & Mair 1983; Bonnavion & Cadot 2018, 2019). These boat-tails are generally formed either by constant-angle surfaces with a salient edge at the upstream junction with the rest of the body, or by curved surfaces leading to a smooth junction.…”

Section: Introductionmentioning

confidence: 99%