Assessment of RANS and DES methods for realistic automotive models

Ashton, Neil; West, Alastair; Lardeau, Sylvain; Revell, Alistair

doi:10.1016/j.compfluid.2016.01.008

Cited by 126 publications

(80 citation statements)

References 29 publications

(74 reference statements)

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“…Compared to classical LES methods, DES save orders of magnitude of computing power for high Reynolds number flows, due to the moderated costs of a RANS model in the boundary layer region, but still offers some of the advantage of a LES method in separated regions. A variant of the DES model, like Improved Delayed DES, IDDES, seems to be attractive [3].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Rans and Des Methods for the Ahmed Body

Guilmineau¹,

Deng²,

Leroyer³

et al. 2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Abstract. This paper presents numerical simulations for the prediction of the flow around the Ahmed body, with the 25• and 35• slant angles, obtained with the flow solver ISIS-CFD. A RANS (Reynolds Averaged Navier-Stokes) turbulence model, as EARSM (Explicit Algebraic Stress Model) and two hybrid RANS-LES models, as DES (Detached Eddy Simulation) and IDDES (Improved Delay Detached Eddy Simulation) models, are used. All these turbulence models are based on the k-ω model.The flow for the slant angle 35• is well predicted by all turbulence models with a slight advantage for the IDDES model. However, for the flow with the slant angle 25• , only the IDDES hybrid RANS-LES model predict the recirculation bubble on the slant.

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Section: Introductionmentioning

confidence: 99%

Assessment of Rans and Des Methods for the Ahmed Body

Guilmineau¹,

Deng²,

Leroyer³

et al. 2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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show abstract

“…Following the superior results provided by LES technique, several researchers have focused on a variety of nuances of complex turbulent flows being predicted by LES and its variations 24,[29][30][31] . Realizing the high computational costs involved with LES, relatively less expensive, yet accurate modelling techniques have evolved and been researched upon in recent times which involve the use of partially averaged Navier Stokes (PANS) modelling and hybrid-RANS modelling 24,[32][33][34] . Although such techniques present an advantage over LES in terms of computational cost-effectiveness, RANS modelling performs fairly in capturing the C-pillar vortices and wake region recirculations accurately, as seen in the past, alongside satisfactory prediction of drag and lift coefficients, which could be used for understanding a novel concept in hand within the lowest simulation runtime.…”

Section: Methodsmentioning

confidence: 99%

Towards a Novel Strategy for Safety, Stability and Driving Dynamics Enhancement During Cornering Manoeuvres in Motorsports Applications

Roy

DasGupta

2020

Sci Rep

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With aerodynamics research being primarily focused on drag and lift mitigation strategies till date, engrossed attention has not been received by the event of numerous accidents caused due to negotiation of turns at high speeds by formula and motorsport cars. We present an unexplored and innovative concept of variable side-flap mechanism with a peculiar orientation for introducing three components of forces in the event of turning. numerical simulations have been performed at two notorious slant angle configurations of the generic ground vehicle body, namely 25° and 35°. In order to analyse the inception of variable forces and flow changes introduced by the flap mechanism, RANS modelling has been performed on nine cases of flap angles from 10° to 90° at six instances of Reynolds numbers between 1.98 × 10 6 and 2.98 × 10 6. in addition to the introduction of variable drag and downforce components leading to decrement in braking effort and enhancement in overall stability and safety characteristics based on steering input, our proposal holds potential for improving driving dynamics by imparting mild oversteer characteristics due to a flap-induced vortex. To conclude, a safe regime of flap operation in terms of flap angle based on drag, downforce and oversteering dynamics has also been recommended. The automotive industry has received a significant amount of attention from researchers worldwide in improving the aerodynamic characteristics of various classes of vehicles, starting from high-speed motorsport cars to heavy load carriers. With the advancement in computational facilities, it has now become possible for simulating the proposed design changes and modifications before arriving at the final design that can be implemented. One of the few objectives of research has been in reducing drag and lift forces associated with the vehicles in motion. This has led to some remarkable aerodynamic designs that we see nowadays in the motorsports industry. Motorsport cars are subject to very high speeds, as a result of which, they experience tremendous amount of lift forces. Front and rear wings are fitted on these cars that generate downforce in order to maintain the overall stability at high speeds 1. The problem exists in the case when such cars have to negotiate turns and twisty sections on the racetrack. Centrifugal force acting on a car is directly proportional to the square of velocity during turn negotiation, and consequently, drivers need to slow their cars down in order to not lose stability. They rely on the downforce generated by front and rear wings and tire friction for successfully negotiating the turn. While Formula 1 wings and tires generate massive amounts of downforce and friction, respectively, several cases of accidents have been reported till date wherein, the drivers lost control of their vehicles while negotiating sharp bends. While such incidents pose a direct threat to life and property, implementation of design additions specifically focused on turn negotiation and the dynamics involved for mitigati...

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“…is obtained when the floor under the model is made as no-slip condition (Shinde et al, 2013;Ashton et al, 2016), i.e., the boundary layer is allowed to developed upstream of the model, where up to 7.0% difference in mean D C…”

Section: O X Y T T Cmentioning

confidence: 99%

Wind noise from A-pillar and side view mirror of a realistic generic car model, DriAver

Ali

Jalasabri

Sood

et al. 2018

IJVNV

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Interior noise of a production car is a total contribution mainly from engine, tyres and aerodynamics. At high speed, wind noise can dominate the total interior noise. Wind noise is associated with the unsteadiness of the flow. For most production cars, A-pillar and side view mirror are the regions where the highly separated and turbulent flows are observed. This study quantifies the wind noise contribution from A-pillar and side view mirror with respect to the interior noise of a generic realistic model, DrivAer. The noise sources are obtained numerically from the flow-structure interactions based on the unsteady Reynolds averaged Navier stokes (URANS) while the noise propagation is estimated using Curle's equation of Lighthill acoustic analogy. The sound pressure frequency spectrum of the interior noise is obtained by considering the sound transmission loss from the side glass by using the mass law for transmission loss. The study found that the noise from the A-pillar is higher than the noise from the side view mirror in the whole frequency range. Near the end of the A-pillar component contributes the highest radiated noise level with up to 20 dB louder than that at the front part of the A-pillar.

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Assessment of RANS and DES methods for realistic automotive models

Abstract: in particular on the use of embedded LES with synthetic turbulence generation. Finally the computational cost of each approach is compared, which shows that whilst hybrid RANS-LES offer a clear benefit over RANS models for automotive relevant flows they do so at a much increased cost.

Cited by 126 publications

References 29 publications

Assessment of Rans and Des Methods for the Ahmed Body

Assessment of Rans and Des Methods for the Ahmed Body

Towards a Novel Strategy for Safety, Stability and Driving Dynamics Enhancement During Cornering Manoeuvres in Motorsports Applications

Wind noise from A-pillar and side view mirror of a realistic generic car model, DriAver

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