Traditionally, wind tunnel testing was a sizeable trial and error process, ongoing throughout the development of a vehicle. Today, with the high level of CAD prediction and pre-production evaluation, coupled with a greater human understanding of aerodynamics, wind tunnel testing often comes into the design process later. The wind tunnel is the proving ground for the vehicle’s form and allows engineers to obtain considerable amounts of advanced information within a controlled environment.

Whilst advanced design processes can anticipate a large proportion of aerodynamic performance, it is still crucial to assess a vehicle in the wind tunnel. Many elements of a vehicle’s form only reveal their behaviour in air flow when carefully tested and cannot be anticipated on computer. The reality of production, tolerances in components and accuracy of build can all play a part in affecting the aerodynamic behaviour of a car.

Aside from engineering concerns, manufacturers are increasingly looking to see how to improve the customer-side of aerodynamics. For example, wind noise from door mirrors is considered very undesirable and can only really be evaluated in a wind tunnel. Other, less obvious issues can also be examined – such as whether air flow forces water through seals or dirt into door apertures.

Sophisticated sound equipment is used in the wind tunnel to compile data on wind noise.

In this photograph, a stream of smoke travels over the vehicle in the wind tunnel as air passes from right to left. It can be clearly seen that laminar air flow remains attached until the very rear of the vehicle, emphasising just how carefully aerodynamic performance has been considered.

All images courtesy & © Ford Motor Company