Particle motion in pressure-driven suspension flow through a symmetric T-channel

Particle motion is studied in pressure-driven suspension flow through a bifurcating channel of square cross-section. Particles and suspending liquid are neutrally buoyant, i.e. of the same density rho. Experi-mental particle trajectories are compared with the computed single-phase flow. The flow is in a symmetric T-junction, with each outgoing stream making a right angle relative to the incoming stream. All branches have the same cross-section and length, with L/D = 29 , where L is the length of each branch, and D is the side length. Particle trajectories are obtained by two-camera imaging for solid volume fraction 0 < phi< 0.30. Inertia is characterized by the bulk, Re = rho DU/eta, and particle scale Reynolds numbers, Re-p = Re(d/D)(2), where d is the diameter of the particles, U is the mean velocity in the inlet channel and eta is the liquid viscosity. In this work, d/D = O(0.1) and Re = 200 . For the pure liquid, spiraling vortices are found in the outlet channels, emanating from near the bifurcation, and these flow structures are largely unchanged for phi <= 0.1, leading to spiraling motions of the particles. Particle tracks are compared against computed tracer motion in the pure fluid flow, and for dilute phi agree qualitatively well, with some deviation due to the particles' finite size. For larger phi, the flow deviates strongly from that of pure fluid, keeping Re = 200 based on the suspension effective viscosity. Vortices are damped for phi = 0 . 2 and disappear for phi = 0 . 30 . Particle interactions with the wall and each other appear to dissipate energy at a higher rate than predicted by the effective viscosity. (C) 2020 Elsevier Ltd. All rights reserved.