How is wind tunnel testing used in vehicle aerodynamic development?

Wind tunnel testing measures aerodynamic forces and flow characteristics under controlled conditions. Tests include: Force measurements (drag, lift, side force) using under-floor balance, surface pressure mapping, flow visualization (smoke, tufts, PIV), acoustic measurements for wind noise, and cooling system airflow evaluation. Full-scale testing uses moving ground simulation and rotating wheels for accuracy. Scale model testing enables rapid screening of concepts. Results validate CFD predictions and guide design refinements. Testing occurs throughout development from concept through production validation.