Vehicle aerodynamics impact of on-road turbulence

• Published in: Proceedings of the Institution of Mechanical Engineers. Part D, Journal of automobile engineering Journal of automobile engineering, 2017-08, Vol.231 (9), p.1148-1159
• Main Authors: Duncan, Bradley, D’Alessio, Luca, Gargoloff, Joaquin, Alajbegovic, Ales
• Format: Article
• Language: English
• Subjects: Aerodynamic forces; Aerodynamics; Automobiles; Automotive engineering; Computational fluid dynamics; Computer simulation; Crashworthiness; Fluid flow; Impact strength; Turbulence; Unsteady aerodynamics; Vehicles; Wind tunnels
• ISSN: 0954-4070; 2041-2991
• DOI: 10.1177/0954407017699710

The ultimate target for vehicle aerodynamicists is to develop vehicles that perform well on the road in real-world conditions. On the other hand, vehicle development today is performed mostly in controlled settings, using wind tunnels and computational fluid dynamics with artificially uniform freestream conditions and neglecting real-world effects due to road turbulence from the wind and other vehicles. Turbulence on the road creates a non-uniform and fluctuating flow field in which the length scales of the fluctuations fully encompass the length scales of the relevant aerodynamic flow structures around the vehicle. These fluctuations can be comparable in size and strength with the vehicle’s own wake oscillations. As a result, this flow environment can have a significant impact on the aerodynamic forces and on the sensitivity of these forces to various shape changes. Some aerodynamic devices and integral design features can perform quite differently from the way in which they do under uniform freestream conditions. In this paper, unsteady aerodynamics simulations are performed using the lattice Boltzmann method on a detailed representative automobile model with several design variants, in order to explore the effect of on-road turbulence on the aerodynamics and the various mechanisms that contribute to these effects.