2 research outputs found
Modeling Electrokinetic Flows with the Discrete Ion Stochastic Continuum Overdamped Solvent Algorithm
In this article we develop an algorithm for the efficient simulation of
electrolytes in the presence of physical boundaries. In previous work the
Discrete Ion Stochastic Continuum Overdamped Solvent (DISCOS) algorithm was
derived for triply periodic domains, and was validated through ion-ion pair
correlation functions and Debye-H{\"u}ckel-Onsager theory for conductivity,
including the Wien effect for strong electric fields. In extending this
approach to include an accurate treatment of physical boundaries we must
address several important issues. First, the modifications to the spreading and
interpolation operators necessary to incorporate interactions of the ions with
the boundary are described. Next we discuss the modifications to the
electrostatic solver to handle the influence of charges near either a fixed
potential or dielectric boundary. An additional short-ranged potential is also
introduced to represent interaction of the ions with a solid wall. Finally, the
dry diffusion term is modified to account for the reduced mobility of ions near
a boundary, which introduces an additional stochastic drift correction. Several
validation tests are presented confirming the correct equilibrium distribution
of ions in a channel. Additionally, the methodology is demonstrated using
electro-osmosis and induced charge electro-osmosis, with comparison made to
theory and other numerical methods. Notably, the DISCOS approach achieves
greater accuracy than a continuum electrostatic simulation method. We also
examine the effect of under-resolving hydrodynamic effects using a `dry
diffusion' approach, and find that considerable computational speedup can be
achieved with a negligible impact on accuracy.Comment: 27 pages, 15 figure