A wind tunnel is a device used to create a stream of air that simulates the conditions of a moving atmosphere. Other terms that can be used to describe a wind tunnel include an aerodynamic test facility, a drag reduction facility or a turbulence simulator. Reynolds experiment chamber is also another synonym for wind tunnel, named after Osborne Reynolds who conducted pioneering research with it in the late 1800s. It's also possible to describe a wind tunnel as an air flow tunnel, a wind channel, or a fluid dynamic laboratory. Additionally, wind tunnels can be classified by their design, such as open-circuit wind tunnels, closed-circuit wind tunnels and hypersonic wind tunnels.