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Modeling the behavior of confined colloidal particles under shear flow
F E Mackay1, K Pastor, M Karttunen
1Department of Applied Mathematics, The University of Western Ontario, Ontario N6A 5B8, London, Canada. fmackay2@uwo.ca cdennist@uwo.ca.
Soft Matter
|September 30, 2014
Summary
Colloidal suspensions confined between walls exhibit quasi-2D ordering under shear. Particle exchange between layers is crucial for transitioning to a disordered phase in these complex fluids.
Area of Science:
- Physics
- Materials Science
- Chemical Engineering
Background:
- Colloidal suspensions are ubiquitous in nature and industry.
- Understanding their behavior under confinement and shear is critical for applications.
- Previous studies often simplified hydrodynamic interactions or confinement geometries.
Purpose of the Study:
- To investigate the behavior of colloidal suspensions under shear between parallel walls.
- To characterize the quasi-2D ordering and phase transitions.
- To develop a phase diagram based on shear rate and volume fraction.
Main Methods:
- Molecular dynamics (MD) simulations were employed to model particle interactions.
- Full hydrodynamic interactions were incorporated using a lattice-Boltzmann (LB) fluid model.
- System parameters included varying volume fractions and steady shear rates.
Main Results:
- A quasi-2D ordered state was observed, featuring coupled layers with distinct densities, order, and granular temperatures.
- A phase diagram was constructed, illustrating the relationship between shear, volume fraction, and layer behavior.
- Particle exchange between layers was identified as a prerequisite for entering the disordered phase.
Conclusions:
- The study reveals a novel quasi-2D ordering in confined colloidal systems.
- The developed phase diagram provides insights into the transitions between ordered and disordered states.
- Hydrodynamic interactions and inter-layer particle exchange are key factors governing suspension behavior under shear.
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