Coarse-grained simulations for flow of complex soft matter fluids in the bulk and in the presence of solid interfaces

Ahuja, V. R.; van der Gucht, J.; Briels, Willem

doi:10.1063/1.4967422

Journal Article

FZJ-2016-06384

Coarse-grained simulations for flow of complex soft matter fluids in the bulk and in the presence of solid interfaces

Ahuja, V. R. (Corresponding author) ; van der Gucht, J. ; Briels, W. (Corresponding author)FZJ*

2016
American Institute of Physics Melville, NY

The journal of chemical physics 145(19), 194903 - (2016) [10.1063/1.4967422]

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Please use a persistent id in citations: http://hdl.handle.net/2128/12912 doi:10.1063/1.4967422

Abstract: We present a coarse-grained particle-based simulation technique for modeling flow of complex soft matter fluids such as polymer solutions in the presence of solid interfaces. In our coarse-grained description of the system, we track the motion of polymer molecules using their centers-of-mass as our coarse-grain co-ordinates and also keep track of another set of variables that describe the background flow field. The coarse-grain motion is thus influenced not only by the interactions based on appropriate potentials used to model the particular polymer system of interest and the random kicks associated with thermal fluctuations, but also by the motion of the background fluid. In order to couple the motion of the coarse-grain co-ordinates with the background fluid motion, we use a Galilean invariant, first order Brownian dynamics algorithm developed by Padding and Briels [J. Chem. Phys. 141, 244108 (2014)], which on the one hand draws inspiration from smoothed particle hydrodynamics in a way that the motion of the background fluid is efficiently calculated based on a discretization of the Navier-Stokes equation at the positions of the coarse-grain coordinates where it is actually needed, but also differs from it because of the inclusion of thermal fluctuations by having momentum- conserving pairwise stochastic updates. In this paper, we make a few modifications to this algorithm and introduce a new parameter, viz., a friction coefficient associated with the background fluid, and analyze the relationship of the model parameters with the dynamic properties of the system. We also test this algorithm for flow in the presence of solid interfaces to show that appropriate boundary conditions can be imposed at solid-fluid interfaces by using artificial particles embedded in the solid walls which offer friction to the real fluid particles in the vicinity of the wall. We have tested our method using a model system of a star polymer solution at the overlap concentration. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4967422]

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