The investigation of gust response problems is a crucial and, if high accuracy is desired, time consuming task. Since linear frequency domain methods have previously shown significant reduction in computational cost for motion-induced aerodynamics, an extension towards gust excitation is proposed. Time-domain signals are reconstructed by a superposition of responses at several discrete frequencies. Once frequency domain solutions are available, a reduced order model is constructed projecting the linearised Reynolds-averaged Navier-Stokes equations on a combined modal basis. While eigenmodes are accurate in predicting structural vibration, additional modes from proper orthogonal decomposition capture aerodynamic effects due to gust excitation. For all methods a two-dimensional NACA0012 aerofoil is investigated at sub- and transonic conditions. Limitations of the linearised approach are first outlined by increasing the gust amplitude at both operating points. Subsequently, a worst case gust length search is performed and it is shown that the computational cost is reduced case dependent by several orders of magnitude compared to the original system.
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