Cake Icing and Climbing Ropes: the Physics of Curling Threads

A stream of honey on toast, a line of cake icing, and a cascading climbing rope all produce similar curlicues and coils as they fall. More than merely decorative, these curls are used to make nonwoven fabrics such as felt, yet are something to be avoided when laying down underwater fiber-optic cables.Many experiments have studied the simple case of a viscous thread falling onto a moving conveyer belt, but until now the physics of how the curls form was a mystery. Simulations of viscous thread p...