Experimental investigation of shear-induced particle migration in steady-state isothermic extrusion

Experimental evidence for radial particle migration in a pressure driven tube flow of a non-Newtonian viscous concentrated suspension will be presented. The suspension is a well-characterized, mono-modal nickel spherical particles having 30% volume fraction. The particles experienced a drift particle concentration profile as a function of the radial position. SEM technique was used to capture micrographs of the sample at various sections in the axial flow direction with a specially designed capillary split die. With the help of image analytical software, the distribution of particle concentration as a function of radial position was obtained. Finally, comparisons were made between experimental results and numerical predictions based on a continuum diffusive-flux model for shear-induced particle migration. Good agreement between experimental observations and numerical predictions indicated that the procedures were useful in capturing particle migration in steady-state isothermic extrusion flow which exhibits a near plug-like concentration profile.