How do you use CFD and wind tunnel testing together for advanced aerodynamic optimization?

Advanced aero development combines CFD for rapid design exploration with wind tunnel for validation and final tuning. CFD (RANS, DES, or LES depending on need) evaluates hundreds of design variants, identifying sensitivities and optimal directions. Wind tunnel confirms CFD predictions, captures effects difficult to simulate (transition, unsteady separation), and enables late-stage fine-tuning. Correlation studies validate CFD setup, with documented delta ranges for different configurations. Key is understanding CFD limitations (separated flows, rotating wheels) and using appropriate methods. Modern approach uses AI/ML for rapid optimization within validated CFD framework.