More Than Meets the EyeHailey SethiAward: Top 100
School: sewanhaka high school When my teacher was showing the class his new butane-fueled soldering iron we quickly noticed the shadows of the invisible gas on our whiteboard. I thought this was an incredible marvel. I found out that the shadows of the butane were visible on the white board because of the projector. The projector's light casting these shadows, as seen in the photo, is similar to a technique called Schlieren photography. Schlieren photography relies on light rays' ability to bend or refract differently depending on the density of the invisible fluid. This allows scientists to observe fluid dynamics in many fields, such as the aerospace industry. One specific example of fluid dynamics that can be observed in this image is the transition from laminar to turbulent flow of the burned gasses. The laminar state of the burned gasses, or the orderly flow, suddenly transitions to the turbulent state, or the disordered flow, due to rapid changes in the gasses' velocity and surrounding pressure. These changes cause the gasses' inertial forces to overcome its viscous forces, becoming disorderly. As seen in the picture, the shadows closest to the soldering iron are in the laminar state, while the shadows furthest from the iron are in the turbulent state with visible eddies, or swirls of the gas. 
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