Munich. When the six new BMW M4 DTMs take their place on the grid for
the DTM season-opener on 6th May 2017, it will mark the temporary end
of a long and intense period of development. A considerable part of
this development took place with the aid of computer simulations. It
is hard to imagine car development without computational fluid
dynamics (CFD) these days.
During the creation of a new race car, the smallest details can bring
about a decisive advantage in the battle for those fractions of a
second on the circuit. It is no wonder that the BMW Motorsport
engineers leave nothing to chance. That is why the CFD flow
calculations are of such special importance. The development of
digitalisation has changed racing car design. Engineers can identify
the most promising solutions for specific components without leaving
the computer.
On computers, the aerodynamics experts simulate the effects of
changes to the individual parts of each car – before the components
have even been built. In the calculation, the model is split into a
grid of 500 million three-dimensional cells, and the virtual airflows
through them. Each of the cells can be separately analysed, sometimes
for an entire day, depending on the type of simulation. Only half of a
vehicle is required, as the air flow for straight-line travel is
identical for both sides of the car.
BMW Motorsport employs experienced aerodynamicists to interpret the
calculated values. Despite the quality of the CFD simulation, the
technical expertise of the aerodynamicists is still a decisive factor
in drawing the correct conclusions from the results. After precise
analysis of the pressure distribution, flow lines and many other
details, the aerodynamicists can make a specific recommendation for
changes to be made to the components. If the part has proved itself
during simulation, variations are tested in the wind tunnel on a
scaled down, 60 per cent model. The computer-aided flow simulation is
not intended to replace wind tunnel work, but complements it.
The preliminary calculations are dealt with by an armada of
high-performance computers. BMW Motorsport uses the BMW cloud system
to dynamically adjust the number of computers in use, and adjust the
load for other users within the BMW Group. This bandwidth and
availability of computing power means that it is possible to perform
multiple calculations in parallel. The result: even more efficiency
and precision in the development of BMW Motorsport racing cars – like
the new BMW M4 DTM.