Spiral Defect Turbulence

When you heat water on the stove, the hot water will swell up from the bottom forming so-called convection patterns. We are doing experiments on the fascinating convection roll patterns that you can find if you heat very thin layers of fluid. The (animated) figure above shows the convecting pattern in our cell (two sapphire plates surrounding a thin horizontal layer of pressurized carbon dioxide gas, heated from below and cooled from above). The fluid flow is visualized by an optical technique, called shadowgraphy. The cell is viewed from above. Warm rising fluid defocuses the light and appears dark, while cold falling fluid focuses the light and appears bright. We call this spiral defect turbulence.