The Effect of Weak Confinement on the Orientation of Nanorods under Shear Flows.

Saman Monjezi,Joontaek Park,James Jones,Alyssa Nelson

doi:10.3390/nano8030130

Saman Monjezi, Joontaek Park + Show 2 more

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https://doi.org/10.3390/nano8030130

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Journal: Nanomaterials	Publication Date: Feb 26, 2018
Citations: 9	License type: CC BY 4.0

Affiliation: Missouri University of Science and Technology

Abstract

We performed a numerical analysis to study the orientation distribution of a dilute suspension of thin, rigid, rod-like nanoparticles under shearing flow near a solid boundary of weak confinement. Brownian dynamics simulation of a rod was performed under various ratios of shear rate and rod diffusivity (Peclet number), as well as the center-of-mass position (wall confinement). We discuss the effects of Peclet number and wall confinement on the angle distributions, Jeffery orbit distribution and average orientation moments. The average orientation moments, obtained as a function of Peclet number and wall confinement, can be used to improve a previous shear-induced migration model. We demonstrate that the improved model can give excellent prediction of the orientation moment distributions in a microchannel flow.

Highlights

There have been multiple studies performed on the orientation dynamics and distributions of rod-like micro/nanoparticles in shear flow because these affect the center-of-mass distributions and rheological properties of the suspension of rod-like particles [1,2]
We investigate the wall confinement effect on the orientation distribution for a rod near a wall under a shear flow
Brownian dynamics simulations were performed by only considering the rod rotation with given various values of Pe and α

Summary

Introduction

There have been multiple studies performed on the orientation dynamics and distributions of rod-like micro/nanoparticles in shear flow because these affect the center-of-mass distributions and rheological properties of the suspension of rod-like particles [1,2]. In contrast to the various studies on the orientation and distribution of rod-like particles, theories on the distribution of rod-like particles near solid boundaries of a microscale flow are not enough to clarify abnormal experimental behaviors. A more accurate calculation of rod distribution under consideration of the steric effect of a wall is required for the prediction of the dynamics and elution behaviors in such a system [12,13]. We focus on the steric effect of a wall on the rod orientation distribution, confined in a channel, of which height is larger than the long axis length of a rod

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Discussion

Conclusion