Inertial particle motion in a Taylor Couette rotating filter

Abstract

In rotating filtration, which is based on supercritical cylindrical Couette flow with a rotating porous inner cylinder, the motion of particles in the suspension depends on both centrifugal sedimentation and transport due to the vortical motion of Taylor vortices. We have simulated the motion of dilute, rigid, spherical particles in Taylor Couette flow using computational particle tracking in an analytic velocity field for flow just above the transition to supercritical Taylor vortex flow. Neutrally buoyant particles follow fluid streamlines closely, but not exactly due to the curvature of the velocity field very near the particle. The motion of particles with a density greater than the fluid is primarily determined by the competition between the centrifugal sedimentation related to the primary cylindrical Couette flow and the secondary radial and axial transport of the Taylor vortex flow. As a result, particles that start near the outer edge of a vortex spiral inward toward a limit cycle orbit. Likewise, particles initially near the center of a vortex spiral outward toward the same limit cycle orbit. Even when a small radially inward throughflow is imposed, particles can remain trapped in retention zones that are away from the wall of the annulus. Consequently, the dynamics of the flow field result in particles tending to be transported away from the porous inner cylinder, thus contributing to the antiplugging character of rotating filter devices.