Entropic Lattice Boltzmann Method for Moving and Deforming Geometries in Three Dimensions

TL;DR

This paper extends entropic lattice Boltzmann methods to three-dimensional, deformable, and turbulent fluid-structure interactions, demonstrating stability and accuracy in complex engineering simulations.

Contribution

It introduces a three-dimensional entropic lattice Boltzmann framework capable of two-way coupling with deformable and turbulent geometries, enhancing simulation robustness.

Findings

Successful simulation of sedimenting sphere validating the coupling algorithm.

Simulation of plunging airfoil at Re=40000 demonstrating turbulence handling.

Model effectively simulates a self-propelled anguilliform swimmer with deformable meshes.

Abstract

Entropic lattice Boltzmann methods have been developed to alleviate intrinsic stability issues of lattice Boltzmann models for under-resolved simulations. Its reliability in combination with moving objects was established for various laminar benchmark flows in two dimensions in our previous work Dorschner et al. [11] as well as for three dimensional one-way coupled simulations of engine-type geometries in Dorschner et al. [12] for flat moving walls. The present contribution aims to fully exploit the advantages of entropic lattice Boltzmann models in terms of stability and accuracy and extends the methodology to three-dimensional cases including two-way coupling between fluid and structure, turbulence and deformable meshes. To cover this wide range of applications, the classical benchmark of a sedimenting sphere is chosen first to validate the general two-way coupling algorithm. Increasing the complexity, we subsequently consider the simulation of a plunging SD7003 airfoil at a Reynolds number of Re = 40000 and finally, to access the model's performance for deforming meshes, we conduct a two-way coupled simulation of a self-propelled anguilliform swimmer. These simulations confirm the viability of the new fluid-structure interaction lattice Boltzmann algorithm to simulate flows of engineering relevance.