Ghost-Mode Filtered Fluctuating Lattice Boltzmann Method

TL;DR

This paper introduces a ghost-mode filtered fluctuating lattice Boltzmann method (GMF-FLBM) that improves accuracy and stability in simulating mesoscopic fluid behavior by selectively eliminating ghost modes while maintaining stochastic forcing.

Contribution

The paper presents a novel GMF-FLBM that enhances fluctuating lattice Boltzmann simulations by filtering ghost modes with minimal changes to existing BGK frameworks.

Findings

GMF-FLBM recovers equilibrium fluctuation amplitudes accurately.

The method maintains stability across a broad range of relaxation times.

Requires only minor adjustments to conventional BGK collision models.

Abstract

Fluctuating lattice Boltzmann solvers are widely employed to model mesoscopic fluid behavior in soft-matter systems, including colloidal suspensions and dilute polymer solutions. Despite their utility, these methods can lose accuracy and stability when non-hydrodynamic modes interfere with the dynamics, especially in single--relaxation-time schemes. Here, we introduce a ghost-mode filtered fluctuating lattice Boltzmann method (GMF-FLBM) for the D3Q27 lattice, obtained by selectively eliminating the propagation of the ghost deterministic content while preserving the necessary stochastic forcing. We show, over a broad range of relaxation times, that GMF-FLBM recovers the amplitudes of equilibrium fluctuations with a comparable accuracy as a fully regularized high-order formulation, while requiring only minor adjustments to the conventional BGK collision framework.