Lattice Boltzmann simulations of soft matter systems

TL;DR

This paper presents a lattice Boltzmann simulation approach for modeling the dynamics of soft matter systems like colloids and polymers, emphasizing hydrodynamic interactions and thermal fluctuations.

Contribution

It introduces a coupled lattice Boltzmann method with detailed boundary conditions and coupling techniques for simulating soft matter in equilibrium and nonequilibrium states.

Findings

Effective simulation of colloidal dispersions and polymers.

Accurate modeling of thermal fluctuations.

Insights into soft matter dynamics under various conditions.

Abstract

This article concerns numerical simulations of the dynamics of particles immersed in a continuum solvent. As prototypical systems, we consider colloidal dispersions of spherical particles and solutions of uncharged polymers. After a brief explanation of the concept of hydrodynamic interactions, we give a general overview over the various simulation methods that have been developed to cope with the resulting computational problems. We then focus on the approach we have developed, which couples a system of particles to a lattice Boltzmann model representing the solvent degrees of freedom. The standard D3Q19 lattice Boltzmann model is derived and explained in depth, followed by a detailed discussion of complementary methods for the coupling of solvent and solute. Colloidal dispersions are best described in terms of extended particles with appropriate boundary conditions at the surfaces, while particles with internal degrees of freedom are easier to simulate as an arrangement of mass points with frictional coupling to the solvent. In both cases, particular care has been taken to simulate thermal fluctuations in a consistent way. The usefulness of this methodology is illustrated by studies from our own research, where the dynamics of colloidal and polymeric systems has been investigated in both equilibrium and nonequilibrium situations.