Transonic buffet is an aerodynamic instability that appears on aerofoils and wings at certain combinations of Mach number and angle of attack, and which limits the aircraft flight envelope. This thesis project presents an experimental
investigation of buffet employing stereoscopic PIV and Background Oriented Schlieren. By using four aerodynamic models, a 2D aerofoil and three 3D wings with sweep angles of 0^o, 15^o and 30^o, the differences between the 2D buffet typical of aerofoils and the 3D buffet typical of swept wings is studied, scrutinising the influence of the sweep angle. The results confirm that for the same aerodynamic conditions the 2D buffet experiences larger shock oscillations than the 3D case. A frequency analysis reveals a clear peak at 160 Hz for the 2D case, which is also visible in the 3D case for low sweep angles. As the sweep angle increases, this peak is replaced by a bump at higher frequencies.