Statistical data characterization and elements of data processing

Wind tunnels are tools used in aerodynamic research to investigate the flow around solid objects. It offers an economical, rapid, and accurate means for aerodynamic research: in the aerospace sector, they allow to investigate the air flow around an aircraft yielding a reduction of the number of flight tests, thus saving time, costs, and even lives. Wind tunnels are usually classified according to the flow regime they can yield: low-speed subsonic wind tunnels, high-speed subsonic and transonic wind tunnels, supersonic wind tunnels, and hypersonic wind tunnels. Shock wind tunnels have been developed based on the same principle of shock tubes to achieve higher Mach numbers. Anechoic wind tunnels have been recently implemented to investigate the sources of noise in the flow and the fluid dynamic phenomena producing these sources. Meteorological wind tunnels are designed to simulate testing in the natural boundary layer, which can be as tall as 500 m.