A passive aerodynamic device for reduced drag can be to provide a desirable shape for the purpose. A side scoop for air inlet is used as an inlet with high efficiency and very low additional drag for the vehicle. It must be located in an area with thin boundary layer and it should be oriented parallel to the flow direction.
The idea is that air flowing towards the narrow opening flows down the ramp of the intake, and the air that approaches from the outside flows over the edges of these diverging scoop walls. Two counter-rotating vortices are generated when the air flows over an edge at an angle, and air will be drawn into the inlet from a diffuser effect. The edges of the scoop are sharp to encourage vortex formation that will draw more air into the inlet. The front edge is important and should have a radius to minimize losses and wake creation at the inlet.
The benefits are low cost and a robust CARBON FIBER design that does not need maintenance. As an air inlet, it may provide a possibility to have an inlet close to the area where the air is needed and avoid long ducting. These types of inlets are used by LOTUS and are more widely used in race-car applications. It has been shown that for automotive boundary conditions, that is, low Mach numbers and a relative bluff body, the impact of the sidewall radius and the inlet aspect ratio is negligible, but the characteristic lip shape, slant angle, cross-flow angle, and boundary layer thickness has a high efficient reducing drag force.