Primary charge effects on prolate spheroids with moderate aspect ratios
Florian Keller1, Hermann Nirschl, Willy Dörfler
1Institute of Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. florian.keller@kit.edu
Journal of Colloid and Interface Science
|August 23, 2011
Summary
Charged spheroidal colloids in linear flow fields exhibit linear relationships between fluid flow and particle forces/torques. Approximate formulas for resistance functions are provided, especially useful for shear flow simulations.
Area of Science:
- Colloid science
- Fluid dynamics
- Electrochemistry
Background:
- Charged colloids are ubiquitous in nature and industry.
- Understanding their behavior in flow fields is crucial for various applications.
- Non-linear effects in the electric double layer can significantly influence particle dynamics.
Purpose of the Study:
- To investigate the behavior of charged spheroidal colloids in linear flow fields.
- To analyze the impact of the electric double layer on particle forces, torques, and motion.
- To develop and validate approximate formulas for resistance functions.
Main Methods:
- Direct numerical simulation using body-fitted grids.
- Solution of the Stokes-Poisson-Nernst-Planck system.
- Efficient semi-implicit time discretization based on Stokes equation splitting.
Main Results:
- Approximating linear expressions found between ambient fluid flow and particle force/torque at low Reynolds numbers.
- Resistance functions show quadratic dependence on zeta potential in the low zeta potential regime.
- Approximate formulas for resistance functions were derived and validated against simulations.
Conclusions:
- The electric double layer significantly affects the hydrodynamic response of charged spheroidal particles.
- Developed approximate formulas can accurately predict behavior and reduce computational cost, particularly for shear flows.
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