How do you analyze unsteady aerodynamic phenomena for flutter and gust response?

Unsteady aerodynamic analysis methods include: Doublet Lattice Method (DLM) for subsonic oscillating lifting surfaces in frequency domain; ZONA51 and similar methods for supersonic; Computational aeroelasticity coupling CFD with structural dynamics; Indicial response methods using Wagner function for step changes; Theodorsen function for reduced frequency effects. Key considerations: reduced frequency k = omega*c/(2V) determines unsteadiness level (k > 0.2 significant); Quasi-steady approximation valid only for k < 0.05; Phase lag between motion and forces affects flutter boundaries. Tools couple with finite element structural models for flutter analysis meeting FAR 25.629 requirements.