A fluctuating lattice Boltzmann method for viscoelastic fluid flows

TL;DR

This paper presents a new fluctuating lattice Boltzmann method for simulating viscoelastic fluids that simplifies stress computation and improves efficiency, validated by classical benchmark problems.

Contribution

It introduces a novel implicit polymer stress fluctuation approach in lattice Boltzmann simulations for viscoelastic fluids, avoiding stress-gradient calculations.

Findings

Accurately reproduces benchmark flow problems

Reduces memory usage and computational cost

Shows excellent agreement with analytical and previous numerical results

Abstract

This study introduces a novel fluctuating lattice Boltzmann (LB) method for simulating viscoelastic fluid flows governed by the Oldroyd-B model. In contrast to conventional LB approaches that explicitly compute the divergence of the polymer stress tensor using finite-difference schemes, the proposed method incorporates the polymer stress implicitly by introducing a polymer stress fluctuation term directly into the evolution equation. This treatment avoids the need for stress-gradient computations, and preserves the physical characteristics of viscoelastic fluid flows. The proposed method is validated against four classical benchmark problems: the simplified four-roll mill, planar Poiseuille flow, unsteady Womersley flow, and the three-dimensional Taylor-Green vortex. The numerical results show excellent agreement with analytical solutions and previous numerical results, confirming the method's reliability in viscoelastic fluid dynamics. Moreover, performance evaluations demonstrate that the present model reduces the memory occupancy and enhances computational efficiency, highlighting its potential for large-scale simulations of complex viscoelastic flows systems.