Molecular orientation in non-Newtonian flow of dilute polymer solutions around spheres

The motion of spheres in non-Newtonian liquids is of widespread and fundamental importance to many complex industrial processes. In the oil, paint, detergent and cosmetic industries, for example, there is the problem of controlling the settling and suspension of particles in non-Newtonian media. Study of the flow around a sphere can also benefit the understanding of complex cyclic flows such as flow through porous media, which are usually modelled experimentally by packed beds of spheres. This aspect of flow around spheres has relevance to gel permeation chromatography (GPC), filtration of polymer solutions, and enhanced oil recovery (EOR). The specific case of a sphere settling under gravity along the axis of a cylindrical tube of twice the radius of the sphere has been chosen as a benchmark problem in viscoelastic flow (Leal et al. 1988). However, the transience of this experiment (including a slow approach to steady state), difficulties with experimental reproducibility and a severely limited range of possible flow regimes (due to the reliance on gravity to generate the flow field) are some of the main reasons why Simon J. Haward Jeffrey A. Odell Molecular orientation in non-Newtonian flow of dilute polymer solutions around spheres