Particle migration in a pillared microchannel

Controlled particle migration in non-Newtonian fluids is very important in many biological, environmental and industrial applications like hydraulic fracturing. The phenomenon of particle transport in non-Newtonian fluid is generally governed by complex interplay of different effects like shear-thinning or thickening behaviour of fluid, viscoelasticity and secondary flow. The present literature on the particle migration in a channel shows that particles move towards the centreline in highly viscoelastic fluids at very low Reynolds number (negligible inertial effects) and move away from the centreline in Newtonian fluids. However, very little is known about how flow and particle dynamics is affected in a rock fracture network or porous medium. To obtain insights into flow dynamics in such a complex geometries, we use microchannels with the specific arrangement of pillars in order to mimic the hydraulic fracture network and porous media. In this study, we perform experiments on the migration of non-Brownian particles in such pillared microchannel of different porosities with different types of fluids - Newtonian, shear-thinning and viscoelastic. The comparison of the particle behaviour in these fluids reveals the influence of the viscous and elastic forces on particle migration. In this work, standard micro-PIV technique is used to obtain the fluid velocity and PTV is used to track the particle velocities. This work provides fundamental insight on effect of viscoelasticity on particle migration in a model fracture network/porous media.