Viscoelastic Flow due to a Rotating Disc Enclosed in a Cylindrical Casing. Influence of Aspect Ratio.

Abstract

This paper deals with viscoelastic flows due to a rotating disc enclosed in a cylindrical casing with variable axial clearances. The characterization for the behaviour of viscoelastic flows due to a rotating disc has been obtained by an experimental study using flow visualization technique and the numerical simulation using several models for constitutive equations. The patterns of secondary flow for the region of competition between the elastic force and the inertial force are a radially arranged double-cell structure (Type DC 1) for small aspect ratio H/R and an axially arranged double-cell structure (Type DC 2) for large H/R.Increasing Re0, the Type DC 2 becomes a radially arranged double-cell structure (Type DC 1′) which is different from the Type DC 1. The Type DC 2 was reproduced qualitatively by numerical simulation with Giesekus model and PTT model, but were not reproduced by numerical simulation with upper convected Maxwell model and power-law model. Furthermore, the profiles of tangential velocity component Vθ and radial velocity component Vr obtained by the numerical simulation with Giesekus model and PTT model for small H/R were in agreement with those measured by using particle tracking velocimetry (PTV).