Effect of microchannel structure and fluid properties on non-inertial particle migration

Journal article (2019)

Authors

R.V. Maitri Eindhoven University of Technology
S. De Shell, Eindhoven University of Technology
S. P. Koesen Eindhoven University of Technology
H. M. Wyss Eindhoven University of Technology
J van der Schaaf Eindhoven University of Technology
J. A.M. Kuipers Eindhoven University of Technology
J.T. Padding Complex Fluid Processing - Mechanical, Maritime and Materials Engineering , Intensified Reaction and Separation Systems - Mechanical, Maritime and Materials Engineering
E.A.J.F. Peters Eindhoven University of Technology
Research Group
Complex Fluid Processing (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2019 R. V. Maitri, S. De, S. P. Koesen, H. M. Wyss, J. van der Schaaf, J. A.M. Kuipers, J.T. Padding, E.A.J.F. Peters
DOI: https://doi.org/10.1039/c8sm02348d
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Published Date

2019

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Complex Fluid Processing

Abstract

In this work, we investigate the influence of channel structure and fluid rheology on non-inertial migration of non-Brownian polystyrene beads. Particle migration in this regime can be found in biomedical, chemical, environmental and geological applications. However, the effect of fluid rheology on particle migration in porous media remains to be clearly understood. Here, we isolate the effects of elasticity and shear thinning by comparing a Newtonian fluid, a purely elastic (Boger) fluid, and a shear-thinning elastic fluid. To mimic the complexity of geometries in real-world application, a random porous structure is created through a disordered arrangement of cylindrical pillars in the microchannel. Experiments are repeated in an empty channel and in channels with an ordered arrangement of pillars, and the similarities and differences in the observed particle focusing are analyzed. It is found that elasticity drives the particles away from the channel walls in an empty microchannel. Notably, particle focusing is unaffected by curved streamlines in an ordered porous microchannel and particles stay away from pillars in elastic fluids. Shear-thinning is found to reduce the effect of focusing and a broader region of particle concentration is observed. It is also noteworthy that the rheological characteristics of the fluid are not important for the particle distribution in a randomly arranged pillared microchannel and particles have a uniform distribution for all suspending fluids. Moreover, discussion on the current discrepancy in the literature about the equilibrium positions of the particles in a channel is extended by analyzing the results obtained in the current experiments.