Real-world wind has a dramatically different effect on vehicle aerodynamics than the idealized conditions of a wind-tunnel, affecting key dimensions like lift, drag, and fuel economy. In the following studies published by SAE., learn how Jaguar Land Rover and Tesla Motors realized better real-world aerodynamic performance using CFD analysis – including real-world wind effects – in Exa’s PowerFLOW.
Abstract, from SAE.org: Under idealised conditions; maintaining measurement repeatability and precision in the assessment of design changes. However, the on-road environment is far from ideal: natural wind is unsteady, roadside obstacles provide additional flow disturbance, as does the presence of other vehicles. On-road measurements indicate that turbulence with amplitudes up to 10% of vehicle speed and dominant length scales spanning typical vehicle sizes (1-10 m) occurs frequently.These non-uniform flow conditions may change vehicle aerodynamic behaviour by interfering with separated turbulent flow structures and increasing local turbulence levels. Incremental improvements made to drag and lift during vehicle development may also be affected by this non-ideal flow environment >> Read more
With Tesla Motors: Application of Real-World Wind Conditions for Assessing Aerodynamic Drag for On-Road Range Prediction
Abstract, from SAE.org: Aerodynamic efficiency, plays an increasingly important role in the automotive industry, as the push for increased fuel economy becomes a larger factor in the engineering and design process. Longitudinal drag is used as the primary measure of aerodynamic performance, usually cited as the coefficient of drag (CD). This drag is created mostly by the body shape of the vehicle, but the wheel and tire system also contributes a significant portion. In addition to the longitudinal drag created by the body and wheels, rotational drag can add an appreciable amount of aerodynamic resistance to the vehicle as well. Reducing power consumption is an especially vital aspect in electric vehicle (EV) design. As the world's first luxury electric sedan, the Tesla Model S combines a premium driving experience with an electric drivetrain package that allows for unique solutions to many vehicle subsystems. The Model S has been developed from its inception with a focus on minimizing aerodynamic drag from all components. To that end, a wheel that reduces aerodynamic power loss was investigated. Exa's PowerFLOW CFD simulation software helped to expedite the design cycle, from force and moment values to qualitative flow visualization. >> Read more