The perfectly aerodynamic ŠKODA OCTAVIA
The fourth-generation ŠKODA OCTAVIA is one of the leaders in its class for aerodynamics. Find out how the company achieved this.
14. 7. 2020 Škoda World INNOVATION & TECHNOLOGY
The development of a new car’s aerodynamics begins with studies that make it possible to suggest measures to reduce the model’s drag. This means that at first most of the work takes place in the virtual environment of simulation programmes using CFD, or computational fluid dynamics. So computers help the developers simulate the behaviour of cars in airflow. “We do about 80% of our work using this method. It’s so accurate that we can base important decisions on the simulation results,” says Pavla Polická, who works on aerodynamics development.
For example, these simulations showed that an active aerodynamic feature known as radiator shutters would reduce drag. The OCTAVIA is first ŠKODA model where this solution comes as standard in all versions. “It’s a very demanding solution, which we developed with the engine specialists right from the start,” says Vojtěch Hudeček on behalf of the Aerodynamics team. The shutter’s four blades can shut off air access to the lower part of the radiator, which improves airflow. “The solution reduces emissions and also saves customers money,” he adds.
Another new aerodynamics feature that proved useful in the very first simulations is the AirCurtain. The wheels are very disruptive for a car’s aerodynamics, but the AirCurtain ensures that air flowing around the bumper creates a kind of aerodynamic curtain around the wheels.
Measuring on 1:1 scale dummy car follows relatively quickly, while numerous other simulations are still taking place. At this point there are still lots of things that can change in a car’s design, so the “car” is made out of cut foam. But there’s a lot of technology hiding under the surface: the engine bay, for example, is fully fitted out, because this has a major effect on the car's aerodynamics.
The behaviour of air at the rear of the car is not only influenced by the design of the rear. Everything is interrelated, so some phenomena occurring at the front can have negative impacts at the rear. “Although there were two different teams working on the OCTAVIA liftback and estate models, they had to cooperate so that their demands for certain parts of the body did not harm the other version’s performance,” say Vojtěch Jakubec and Vojtěch Hudeček, who led the two teams. The result of this cooperation is clear: both versions are aerodynamically excellent. The large spoiler on the boot door helped considerably on the estate version, for example.
The wheels are a kind of alchemy. “Working with the design team, we managed to make them aerodynamic and beautiful at the same time,” Jakubec says with pride. As well as CFD, ŠKODA uses a unique technical solution for wheel development, which makes it possible to quickly test various 3D-printed wheel shapes in a wind tunnel. Every different wheel design and size has a different effect on a car’s aerodynamics. The WLTP standard makes it necessary to test every alternative for the purpose of emissions reporting.
Complete car prototypes come to the fore in one of the last phases of aerodynamics development. Contrast colours are used in the wind tunnel to check how water travels over the car body in motion, for example. This is done because the carmaker needs to make sure that drivers can see well out of their side windows and rearview mirrors, for example.
The final phase of the aerodynamics team’s work involves measuring final prototypes’ results in the wind tunnel for the homologation of all versions. For this purpose, it makes use of the Volkswagen Group and Audi tunnels as well as the Stuttgart university wind tunnel.
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