In the last week’s article, we discussed predictive tools used for aerodynamic development. This week we will talk about CFD applied to motorsport aerodynamics.

CFD stands for Computational Fluid Dynamics; it is vastly used in motorsport to support the evaluation of the aerodynamic performance of car designs. The usefulness of CFD for such a complex application has increased considerably over the last two decades with the progress in computational power availability, cost reductions and code developments.

The adoption of CFD as a development tool requires a relatively low upfront investment, the primary investments being high-performance clusters (when cloud computing is not a suitable option), CFD licences when applicable and methodology development.
An extensive range of CFD modelling approaches is available. The cheaper and quicker methods use coarser discretization and significant approximations in the turbulence modelling, while the more expensive strategies resolve the flow and turbulence in more detail.

Choosing where to sit within this range of modelling options is not straightforward. In addition to the costs mentioned above, in motorsport, the opportunity cost plays an even more critical role than in other industries.
A team cannot afford only to perform high-resolution CFD simulations if those take days to run. In addition, teams need to develop their packages quicker than their competitors to win races; they need to test multiple concepts and operating conditions over relatively short periods, and this approach is not compatible with very high-resolution CFD models.

Accuracy of the modelling is essential; nobody will argue that “fast and wrong” is better than “slow and right”; however, there are multiple options in between these two scenarios which are very much suitable for motorsport, the choice of the modelling approach has to consider the overall level of understanding of the system, the stage of development, the timescales and the budget available. Teams often have multiple modelling options available to deploy, with lower-resolution models used for bulk development and higher resolution for correlation exercises.

In the following article, we will draw comparisons between CFD and Wind Tunnel, discussing the strengths and limitations of each, the way they are used and their role in car aerodynamic development.