FLOW OF A VISCOELASTIC FLUID BETWEEN ECCENTRIC CYLINDERS - IMPACT ON FLOW STABILITY

The flow of an elastic fluid between eccentric cylinders was experimen tally and theoretically examined. A purely elastic flow instability in the eccentric cylinder flow geometry has been discovered [1,2]. The f ocus of this paper is an investigation of how the characteristics of t he base flow ultimately influence the how stability. The velocity prof iles of a Boger fluid between eccentric cylinders was measured by Lase r Doppler velocimetry and compared to the theoretical predictions from a lubrication analysis. The base how stress profiles between eccentri c cylinders were calculated by integrating the polymeric stresses alon g streamlines. It is shown that the convection of polymeric stresses a lter the hoop stresses in the flow. Implications of this observation t o the flow stability are discussed. (C) 1998 Elsevier Science B.V. All rights reserved.