Rotating spiral are mystical. Surely, Mowgli falls asleep and we all know what happened next. We see spiral patterns in our everyday life on T-shirts, in art, or sometimes even rotating in advertisements. These patterns can still be admired at the burial grounds at Newgrange in Ireland. Indeed spiral patterns are not at all a human invention.
Nature abounds with spiral patterns from the shape of nautilus shells to that of galaxies.
Indeed we know that rotating spirals may appear in many chemical, biological and physical systems that are driven out of equilibrium. In these systems external driving is generating ordered patterns. A good example is a hurricane which is caused by hot air up-welling from the ocean surface which was in turn heated by the sun. Bodenschatz and coworkers are investigating rotating spiral waves in a system that very much resembles a cooking pot. A shallow horizontal fluid layer is contained between two plates which are heated from below and cooled from above.