Purely Elastic Instabilities in Viscometric Flows

TLDR

Purely elastic flow instabilities, occurring without inertial forces, are reviewed in viscometric measurement flows—a relatively new field driven by experiments, simulations, and analytic theory, and the examined simple flows are critical to rheological measurement devices. The study examines how elasticity alone in homogeneous polymeric flows can induce flow bifurcation and change. The authors review experiments, simulations, and analytic theory to elucidate the novel physical mechanisms by which elasticity alone induces flow bifurcation in homogeneous polymeric fluids. The knowledge gained is broadly applicable to more complex flows exhibiting similar elastic instabilities.

Abstract

Purely elastic flow instabilities-those occurring in the absence of inertial forces-in flows used for the measurement of fluid viscometric parameters are reviewed. In particular, we examine the growing body of knowledge surrounding how the presence of elasticity in homogeneous, flowing polymeric fluids can act in isolation to create flow bifurcation and change. The field of inquiry is relatively new, and the studies that have played a key role in developing the science include a balance of experiment, large-scale computer simulation, and analytic stability theory. All are reviewed with a focus on how each has contributed to the understanding of novel physical mechanisms and principles governing these instabilities. The flows examined are simple, but critically important to the measurement devices common to tne laboratories of rheologists and fluids engineers. Moreover, it is clear that the knowledge gained from these studies may be generally applicable to a wide range of much more complicated flows that demonstrate this type of instability.