A Novel Particulate Separation Method

Cornell University, Ithaca NY

Investigators

Abstract

The low Reynolds number motion of freely-suspended particles in bifurcations of capillary tubes will be studied experimentally. A bifurcation is a point where a tube splits to form two tubes. When a suspension of particles flows through a bifurcation, the partitioning of particles between the downstream branches differs from the partitioning of total volume (particles + suspending fluid) between the branches. The difference results from a combination of hydrodynamic interactions between the particles and the bifurcation wall and the exclusion of particles from a thin layer near the walls. This principle will be investigated with the aim of designing a device to separate particles from fluid. Particle trajectories will be measured experimentally, and the effects of bifurcation geometry, particle size, and particle volume fraction will be determined. Experimental results will be combined with numerical models based on mass and momentum conservation to predict the motion and flux of particles in networks of channels and build a framework for the rational design of a separation device. Many manufacturing processes of biological and technological importance involve suspensions of solid particles in a viscous liquid. Separating freely-suspended particles from the surrounding liquid can pose significant technical challenges, especially in cases where the particles are nearly neutrally buoyant in the suspending medium. This project will explore the motion of particulate suspensions as they flow through branching tubes, and will use certain characteristics of the flow to design a new particle separation method. The process has significant potential advantages over traditional methods, such as membrane-based separations. The goal of the research is to design a continuous, stagewise separation process that requires little maintenance or control, is relatively insensitive to ambient conditions such as temperature and pressure, and requires no purging or disposal of filter elements.