CFD: digitial advantage

Modern racing cars – and, in fact, a lot of technology – spend a lot of their development time on computers, before material takes any shape. Computational fluid dynamics, or CFD, is a keystone to designing complex modern machines, especially the 2017 BMW M4 DTM.

What is cfd?

Simply, computer programs analyse shapes in near-infinite detail, providing information for BMW Motorsport’s aerodynamicists to analyse. They can then make small changes, repeat the test – and so on. That way, huge costs in track time and physical resources can be saved before the car even hits the track.

Though the data is impressive, it is nothing without a human element: BMW Motorsport's team of aerodynamicists work closely with the data.

Though the data is impressive, it is nothing without a human element: BMW Motorsport's team of aerodynamicists work closely with the data.

How does it work?

A computer-generated model is created – you only need half the car, as predominantly CFD works on straight-line aerodynamics, which are identical on each side – and split into a grid of 500 million three-dimensional cells. Each of the cells can be separately analysed, and the whole process can take an entire day. The data created by the computer can then be analysed in minute detail by the aero experts, who then can direct their design strategy and any changes based on the intelligence. Within BMW Motorsport, the BMW cloud system is used, which dynamically adjusts the number of computers in use at any one time, adjusting the load for other users within the BMW Group. Despite the high demand placed on the system, high bandwidth and computing power means it’s possible to perform multiple calculations at once.

What are the advantages?

The biggest advantages are twofold. Firstly, savings in time, money and resources – the cars still need to be physically tested, but the amount of time and money spent testing can be vastly reduced with good CFD work. Secondly, because of the power of the computing and the new information it can bring to the table for the designers, the cars can be faster and more efficient – just as a racing car needs to be. That means more trophies.