Numerical study of particle harvesting in micro-channels

Details

Supervisors

Papalexandris, Miltiadis

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil mécanicien

Abstract

In this master thesis, we are completing a numerical study of the Poiseuille flow of dense non-colloidal mono-disperse suspensions in micro-channels at low-Reynolds number. The end goal is to estimate the feasibility of a passive and continuous particle harvesting system taking advantage of the shear induced particle migration phenomenon. The first part is dedicated to a literature review where we are describing the characteristics of dense suspensions and the different theoretical models used to describe the tendency of particles to migrate to the center of the channel. Then, we develop the governing equations used to model the behaviour of the suspensions taking for hypotheses that the solutions are time independent and that the variables are uni-directional. These equations are based on a recently developed two-phases model. The migration of the granular phase is based on a advection-diffusion model in the form a compaction equation that evaluates the granular pressure with the intergranular stresses and a diffusion term. Finally, we present and discuss the different obtained numerical results. First, we study horizontal channels where the suspension is driven by a pressure gradient. Secondly, we compare these results with gravity driven flows in vertical channels in order to evaluate the performance of a passive particle harvesting system. The parameters we analyse are the average particle volume fraction, the channel height and the velocity reached at the center. Then, we analyse how modifying these impact the mass-flow of collected particles with the help of mass-flow coefficients. We also analyse the impact of the used draw law, the domain size and the boundary conditions. The last section is a comparison with dry granular media.