Sand falling through water creates turbulence and complex patterns.
Settling Column demonstrates that sand falling through water forms complex patterns. The visitor turns a tube of sand and blue liquid over to cause the sand to fall. The angle of the tube affects the patterns of flow. As the sand falls, it displaces water at the bottom of the tube causing the fluid to flow upwards. When this up welling encounters more falling sand, much turbulence is created. The more vertically the tube is oriented, the greater the turbulence and the longer the sand takes to settle.