Flow 5.0 is an interactive art installation consisting of hundreds of ventilators, each being controlled individually by various sensors.
Microphones and other sensors control the direction and speed of the fans as visitors pass through a corridor. The fans form the walls of the corridor, and they remain off until a visitor moves in front of them.
Daan Roosegaarde, the creator of Flow 5.0, describes it as an interactive landscape made out of hundreds of ventilators which reacts on your sound and motion. By walking and interacting the visitors creates an illusive landscape of transparencies and artificial wind.
Further reading on Studio Roosegaarde's website.
Also check out the video of the installation.