How do you analyze and reduce aircraft aerodynamic noise sources?

Aeroacoustic analysis identifies and mitigates noise sources: Jet noise analyzed using acoustic analogies (Lighthill, FW-H) and LES; Airframe noise from landing gear, flaps, slat gaps requires high-fidelity unsteady simulation; Fan and turbomachinery noise uses duct acoustic methods. Reduction strategies include: Chevron nozzles for jet mixing noise; Slat cove treatments and sealed slats; Flap side-edge treatments and continuous moldline flaps; Landing gear fairings; Porous or serrated surfaces for turbulent boundary layer trailing edge noise. Certification requirements (ICAO Chapter 14) drive design, with noise prediction using semi-empirical methods calibrated to flight test data.