A few years ago, when Jaguar engineers commenced work on the recently introduced XE small sedan, they took what then seemed like a risky break from normal practice. Instead of building full-size clay models to develop the XE?s exterior details in a wind tunnel, they took a chance on a technology called Computational Fluid Dynamics (CFD). This enabled faster and less expensive development using digital simulation models instead of traditional physical prototypes. And a better chance of beating the class-leading BMW 3-series aerodynamic performance.
Wind tunnels were invented in the 19th century to test aerodynamic properties. The Wright brothers used one to develop their Flyer in 1901 and Gustav Eiffel conducted thousands of tests in a tunnel built near his Parisian tower. Today, wind tunnels are a key means of reducing aerodynamic drag to boost fuel economy as every maker strives to meet daunting federal mpg requirements on the books for 2025. But the success both Jaguar and Tesla have achieved developing cars with CFD suggests there?s a new kid on the testing block which might knock the wind out of wind tunnels. CFD has existed for half a century but recent strides in computing power are finally making this branch of fluid mechanics useful to car developers. In the most modern CFD simulations, air molecules flow on streamlines that travel over, under, or though a hypothetical car. Every change in a molecule?s momentum as it moves around the car results in a small force ...