Numerical study of flow control strategies for a simplified square back ground vehicle

Eulalie, Yoann; Gilotte, Philippe; Mortazavi, Iraj

doi:10.1088/1873-7005/aa5c54

Cited by 15 publications

(14 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, [9] found the optimal angle for an elliptical flap to be 50° from the horizontal but on the contrary, [4] achieved a 20° optimal angle over a square back car. Furthermore, [28] found a 12° optimum angle over a square back Ahmed body with small flaps at the rear. Though all these cases are investigated over a blunt trailing edge, the reported maximum drag reduction differs significantly in terms of the implementation angle.…”

Section: Resultsmentioning

confidence: 87%

Drag Reduction On A Square Back Ahmed Body Using A Simple Flap

Siddiqui¹,

Agelin‐Chaab²

2021

Progress in Canadian Mechanical Engineering. Volume 4

View full text Add to dashboard Cite

A simple passive flap device has been applied over a square back Ahmed body. A parametric study varying the angle of implementation, length, width, and ground clearance has been carried out to calculate the optimum size of the flap and ground clearance. It was found that a flap with 135mm length and 389mm width at a 10° implementation angle provides 8.8% of drag reduction. Furthermore, the same flap enhanced this reduction to 12.5% at 25mm ground clearance. The study is conducted using Ansys Fluent at a Reynolds number of 7.8 x 10 5 while employing the SST k-omega model. Vortex identification methods namely Q-criterion and Lambda-2 criterion have been used to further elaborate the change in flow topology due to this passive flap device. However, a detailed study is underway to precisely define the nature of such modifications.

show abstract

Section: Resultsmentioning

confidence: 87%

Drag Reduction On A Square Back Ahmed Body Using A Simple Flap

Siddiqui¹,

Agelin‐Chaab²

2021

Progress in Canadian Mechanical Engineering. Volume 4

View full text Add to dashboard Cite

show abstract

“…Figure 14 shows the translucent isosurfaces of the pressure coefficient (C p ) behind the base of the GTS model at the specified yaw angles of the incoming flow, overlaid with the vortex cores obtained from the time-averaged flow by using the method detailed in [72]. Similar to the pressure coefficient torus observed in the wake of squareback bluff bodies ( [2,15,21,33,42,77] and others), a torus tilted in the streamwise direction is observed behind the GTS for β = 0 • (Fig. 14a), with the bottom of the torus further away from the top on account of the flow asymmetry (and where the smaller vortex (C) occurs in the vertical midplane).…”

Section: Influence Of the Yaw Angle (β > 0 • )mentioning

confidence: 92%

An LES Investigation of the Near-Wake Flow Topology of a Simplified Heavy Vehicle

Rao

Zhang

Minelli

et al. 2018

Flow Turbulence Combust

View full text Add to dashboard Cite

Recent experimental investigations by McArthur et al. (J. Fluids Struct. 66, 293-314, 2016) in the wake of a simplified heavy vehicle or commonly known as the ground transportation system (GTS) model has shown that the flow topology is invariant over a large range of Reynolds numbers [2.7 × 10 4 − 2 × 10 6 ]. Numerical simulations are performed to investigate the initial flow topology at a Reynolds number of 2.7 × 10 4 , using well-resolved large eddy simulations (LES). In the vertical midplane behind the GTS, a flow state which is anti-symmetric to that reported in McArthur et al. (J. Fluids Struct. 66, 293-314, 2016) is observed here, thereby, confirming the possibility of occurrence of the complementary bi-stable flow state. The occurrence of this bi-stable state does not depend on the ground clearance between the GTS and the ground plane, as a similar flow topology is observed at both small and large gap heights. Furthermore, the flow topology in the vertical midplane is also found to be insensitive to the incoming flow for small yaw angles. However, complex flow behaviour is observed in the wake for larger yaw angles, where the flow topology in the vertical midplane becomes nearly symmetric, while an asymmetric flow topology is now observed in the lateral midplane in the near wake. Furthermore, the corner vortices which originate from either side at the front of the model merge in the far wake, leading to a large vortex structure nearly equal to the height of the model. The near-wake topology of the GTS is analysed and compared with previous studies for a range of scenarios, and the forces on the GTS are computed.

show abstract

“…10. These images are analogous to the pressure coefficient on the base of the squareback Ahmed body (Lucas et al (2017), Eulalie et al (2017)), when conditionally-averaged over one flow state. While the pressure coefficient is symmetrical about the lateral midplane for the squareback Ahmed body, they are symmetrical about the vertical midplane for the GTS (also see McArthur et al (2018)).…”

Section: β ¼ 0 ∘mentioning

confidence: 99%

“…These studies indicate that two flow solutions are possible in the wake of the GTS, and the switching between two flow states is usually observed in the experimental studies, where the phenomenon is referred to as bistability (or the random occurrence of the bi-stable states/bi-modal solutions), and has been observed in the wake of squareback bluff bodies (Volpe et al (2014a), Volpe et al (2015), Grandemange et al (2013a), Herry et al (2011), Grandemange et al (2013b), Lahaye et al (2014), Grandemange et al (2014), Lucas et al (2017), Evrard et al (2016), Varon et al (2017), Eulalie et al (2017), Bonnavion and Cadot (2018) and others). Only one of the two possible flow states is usually observed in numerical simulations, which are usually performed for a finite time as compared to experimental studies, which are carried out for much longer time periods.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the near-wake flow topology of a simplified heavy vehicle using PANS simulations

Rao

Minelli

Zhang

et al. 2018

Journal of Wind Engineering and Industrial Aerodynamics

View full text Add to dashboard Cite

The near-wake flow topology of a ground transportation system (GTS) is investigated using partially-averaged Navier-Stokes (PANS) simulations at Re ¼ 2:7 Â 10 4. Recent numerical investigations for the GTS model using large eddy simulations (LES) showed an anti-symmetric flow topology (flow state II) in the vertical midplane compared to that observed in previous experimental studies (flow state I). The geometrical configuration of the GTS permits bi-stable behaviour, and the realisation of each of the two flow states, which are characterised by an asymmetrical flow topology, is achieved by varying the differencing scheme for the convective flux in the PANS simulations; AVL SMART schemes predict flow state I, while central differencing scheme (CDS) predicts flow state II. When the GTS model was placed away from the ground plane, the AVL SMART scheme fails to predict the flow asymmetry resulting in a pair of symmetrical vortices in the vertical midplane, while flow state II topology is observed when CDS is used. The switch from flow state I (II) to flow state II (I) is achieved by changing the numerical scheme from AVL SMART (CDS) to CDS (AVL SMART), with an intermediate transient-symmetric (TS) state being observed during the switching process. The numerical scheme in the PANS simulations thus plays a critical role in determining the initial flow topology in the near wake of the GTS.

show abstract

Numerical study of flow control strategies for a simplified square back ground vehicle

Cited by 15 publications

References 25 publications

Drag Reduction On A Square Back Ahmed Body Using A Simple Flap

Drag Reduction On A Square Back Ahmed Body Using A Simple Flap

An LES Investigation of the Near-Wake Flow Topology of a Simplified Heavy Vehicle

Investigation of the near-wake flow topology of a simplified heavy vehicle using PANS simulations

Contact Info

Product

Resources

About