An S-duct, but what for?
The purpose of this system, which can also be found on the RB11, is to solve certain aerodynamic problems that occur under the nose. The idea is to prevent as much as possible airflow disruption upper and under the car’s nose, over a relatively long surface. Aerodynamicists refer to this air as the ‘boundary layer’.
As can be seen in the diagram below, when air passes over a surface, one can see that the particles that are closest to the surface move slower than those that are further away. Indeed, even a very smooth finish can seem like sandpaper when looked at under a microscope. The air that meets this surface is therefore progressively slowed, until it almost stops when in direct contact with the surface.
The layer of air that is slowed significantly is referred to as the ‘boundary layer’ and is of variable thickness depending on the material, the angle of incidence and other parameters. The slow air rubs against the fast air, creating turbulence, which in turn creates drag.
