Influence of Particle Rotation on Radial Migration in the Poiseuille Flow of Suspensions

Abstract

Segré and Silberberg¹ recently observed that when an initially uniform dilute suspension of rigid spheres passes through a circular tube in laminar flow, the spheres tend to concentrate into an annular region about half-way between the tube centre and tube wall. It was suggested that the inward motion of the spheres resulted from a force, akin to the Magnus effect, which was present because the spheres rotated as they passed through the tube. Work by Tollert², Saffmann³ and Rubinow and Keller⁴ has also indicated the presence of an inward force of the above type, while the ‘minimum energy dissipation’ theory of Jeffery⁵ shows that the spheres should move inwards and eventually travel along the tube axis. Unfortunately no satisfactory explanation has been given of the fact that, in the above experiment¹, the inner spheres moved outwards while the outer spheres ceased to move inwards when they reached the region of the annulus.