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The new BMW Aerodynamisches Versuchszentrum (AVZ) wind tunnel center includes a full-scale wind tunnel, "The BMW Windkanal" and an aerodynamic laboratory "The BMW AEROLAB." The AVZ facility incorporates numerous new technology features that provide design engineers with new tools for aerodynamic optimization of vehicles. The AVZ features a single-belt rolling road in the AEROLAB and a five-belt rolling road in the Windkanal for underbody aerodynamic simulation. Each of these rolling road types has distinct advantages, and BMW will leverage the advantages of each system. The AEROLAB features two overhead traverses that can be configured to study vehicle drafting, and both static and dynamic passing maneuvers. To accurately simulate "on-road" aerodynamic forces, a novel collector/flow stabilizer was developed that produces a very flat axial static pressure distribution. The flat static pressure distribution represents a significant improvement relative to other open jet wind tunnels.

The range of applicability and the physical restrictions for the use of ground-simulation techniques in automotive wind tunnels are elucidated. The techniques considered are the moving-belt technique, as well as boundary layer control techniques like tangential blowing and distributed normal suction for use in wind tunnels with stationary ground boards. Attention has to be paid to the question of whether the flow to be simulated is of boundary layer or Couette type. In the case of boundary layer flow, interaction of the ground-floor boundary layer with the inviscid flow in the gap between a vehicle and the road can be fully simulated by introducing a negative transpiration velocity along the stationary ground plane. In practise however, angularity effects on the external flow result from mismatched control parameters. Very small relative ground clearances give rise to the formation of a Couette flow between the road and the vehicle.