A smoke wind tunnel, also called a flow visualisation tunnel, is used to explore aerodynamics and engineering. The wind tunnel duplicates the effect of fast-moving air. The smoke makes air flow visible.
Use mini wind tunnels to explore the aerodynamic properties of models. Aviation engineers use wind tunnels to see how planes would behave in flight. Architects use them to see the effect of high winds on structures like skyscrapers or bridges.
Build your own wind tunnel using a box fan to provide the "wind." The tunnel itself can be constructed from plywood or corrugated cardboard covered with transparent plastic sheeting or rigid transparent acrylic (Plexiglas, perspex).
Make smoke using smouldering materials such as paper or cardboard. Dry ice throws off visible "smoke" (really vapour) when it comes into contact with the air. Feeding light, fine powder such as baby powder into the wind tunnel also makes air currents visible. Do not inhale smoke, vapour or powder.