Forms And Patterns Of Viscous And Elastic Threads
Dr. Neil M. Ribe
Date & Time
Room 7-37, Haking Wong Building, HKU
Thin threads of viscous fluid are geometrically nonlinear objects that are capable of a wide range of pattern-forming behaviors. The best-known of these is “liquid rope coiling” (LRC), which occurs when a viscous thread falls vertically onto a horizontal surface. I and my colleagues have shown that LRC can occur in four distinct modes, each representing a different balance of the viscous, gravitational and inertial forces acting on the thread. We have also found experimentally a novel “liquid supercoiling” state in which the coiled structure formed by LRC undergoes slower econdary coiling. Another novel phenomenon is the generation of spiral bubble waves by LRC via slow precession of the center of coiling. A still richer system is the “fluid mechanical sewing machine” in which a viscous thread falls onto a moving belt, where it lays down more than a dozen complex “stitch” patterns. To close this talk, I will briefly review some analogous phenomena involving elastic threads.