Field velocity method (FVM) with gust source terms method was applied to study the response of a flat plate wing encountering a large transverse gust at low Reynolds flow. The gust is modeled by a "sine-squared" profile with maximum magnitude equal to 80% of the freestream velocity. During the gust encounter, the flat plate experiences large unsteady forces, associated with formation of LEV and massive shedding. This study aims to investigate the effect of gust width on the produced forces on a flat plate at two angles of attack, 0° and 45°. Computations show that the initial condition of the flow around the airfoil and gust width affect the forces. The maximum lift, as a function of gust width, increases in a similar manner to Kuessner's function, asymptotically approaching a fixed value. For pitch angle 0°, the lift peaks align well with Kiissner's solution for a step-function gust. At pitch angle 45° and gust width of 4 chords or smaller, the normal force drops below the steady-state value when the wing exits the gust. For a 9 chord width gust, the normal force does not drop below the steady-state value.
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