In this work, full 3-D numerical simulations are performed to study the combined effects of elastic and inertial forces along the Y and Z-midline of the channel. Ultimately, simulation results are compared and matched with experimental fluorescent streak images of the focusing of particles under the same parametric conditions. We reported that shear-gradient (FSG), N2-induced secondary flow transversal drag (FSF), and elastic (FEL) lift are the main forces responsible for the focusing of particles in the elasto-inertial regime.
This content will become publicly available on December 1, 2023
Elasto-Inertial Focusing Mechanisms of Particles in Shear-Thinning Viscoelastic Fluid in Rectangular Microchannels
Growth of the microfluidics field has triggered numerous advances in focusing and separating microparticles, with such systems rapidly finding applications in biomedical, chemical, and environmental fields. The use of shear-thinning viscoelastic fluids in microfluidic channels is leading to evolution of elasto-inertial focusing. Herein, we showed that the interplay between the elastic and shear-gradient lift forces, as well as the secondary flow transversal drag force that is caused by the non-zero second normal stress difference, lead to different particle focusing patterns in the elasto-inertial regime. Experiments and 3D simulations were performed to study the effects of flowrate, particle size, and the shear-thinning extent of the fluid on the focusing patterns. The Giesekus constitutive equation was used in the simulations to capture the shear-thinning and viscoelastic behaviors of the solution used in the experiments. At low flowrate, with Weissenberg number Wi ~ O(1), both the elastic force and secondary flow effects push particles towards the channel center. However, at a high flowrate, Wi ~ O(10), the elastic force direction is reversed in the central regions. This remarkable behavior of the elastic force, combined with the enhanced shear-gradient lift at the high flowrate, pushes particles away from the channel center. Additionally, a precise prediction of more »
- Publication Date:
- NSF-PAR ID:
- 10390288
- Journal Name:
- Micromachines
- Volume:
- 13
- Issue:
- 12
- Page Range or eLocation-ID:
- 2131
- ISSN:
- 2072-666X
- Sponsoring Org:
- National Science Foundation
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