The Swiss aerodynamics specialist – who you can catch speaking live at the Free-to-Attend Technology Demonstration Area at Automotive Testing Expo Europe 2019 – explains how wind tunnels and CFD can be combined effectively
How are wind tunnels and CFD used in combination at Sauber Aerodynamik?
We are only permitted 65 runs in the wind tunnel each week, so we maximize what we can do, within the rules, in each run. This means synchronized robotic motion and a comprehensive aerodynamic map from pretty much each run. In a few minutes of running in the wind tunnel, the model of the car can be mapped in relative detail. These models are packed full of sensors. Off-body airflow information can also be gathered via PIV [particle image velocimetry] or motorized mechanical probes. Despite restrictions on the maximum allowed CFD solving power that we can use, the number of configurations that can be tested is more than an order of magnitude higher in CFD. The time needed to create a top-quality mesh is unrestricted, so the quality of cells used can be optimized, while attempting to minimize cell count. Post-processing work is also unrestricted, so we maximize this time.
CFD enables us to gain an understanding of mechanisms, and create and evolve new flow-management ideas. It can be used in various different areas, for instance in cooling and liquid flow management.
How do you expect the technique to evolve and develop over the next few years?
Rules play a big part in the evolution of the R&D techniques. In the automotive industry, the need to speed up development cycles while reducing costs is likely to steer the evolution of the technique in the same direction as in motorsport. This may mean more adaptable physical models and better use of computational power. In motorsport, research methods are likely to continue along the same lines as in the last 10 years – in the short term, at least. In 2021, when new team agreements facilitate more fundamental rule changes, we expect to also need to make more fundamental changes to how research is done.
What will this be driven by?
Hardware improvements are enabling, at the same cost, more accurate results from CFD. Once a brick has been streamlined into a sleek shape, the next big improvements require more effort. What has been interesting for us is that software has played such a big a part in what can be achieved with the hardware, and how long it takes to achieve these results. Both will affect how we conduct research in future.
More in the March 2019 issue of ATTI (p155).