(590e) Flow-assisted Polymer Degradation in Turbulent  Boundary Layers

Jack Zakin and others pioneered work in the early 1970s on flow-induced degradation of drag reducing polymer solutions. It was demonstrated that the stresses within capillary tubes were sufficient to mechanically degrade polymers. In spite of these early observations, most experts in the early 2000s thought that polymer degradation played a negligible role within turbulent boundary layers. This was based on numerous water tunnel tests showing drag reduction was independent of the wall shear stress. However, tests in the Large Cavitation Channel (the world’s largest water tunnel) showed that drag reduction was speed dependent. These observations led to a revisiting of flow-induced degradation and a scaling law dependent on shear rate and residence time. This presentation will discuss the forming and implications of this scaling law as well as how the pioneering work of Jack Zakin contributed to its development.