Flow structures and stability in Newtonian and non-Newtonian Taylor-Couette flow

Abstract

In the present paper the pattern formation and stability of Newtonian and non-Newtonian fluid in a wide-gap Taylor-Couette system (ri/r0 = 0.5) is investigated. Flow visualization and measurement of two-dimensional flow fields with Particle Image Velocimetry are performed in silicone oil as reference fluid and in a viscoelastic Boger fluid. Here we present first results regarding the influence of the boundaries on the fluid flow at moderate aspect ratios. The transition sequence in the Boger fluid is similiar to a Newtonian fluid at lower rotation rates of the inner cylinder. Due to the studied range of aspect ratios the fluid flow behaviour is strongly influenced by the boundaries. In the Boger fluid the wavy vortex flow is inhibited for aspect ratio Γ < 4.48.The observed wavy vortex flow in the Boger fluid is damped in comparison with Newtonian fluid.