The lattice-Boltzmann method and its applications in acoustics. Developing code for applications in acoustics using the lattice-Boltzmann method

Abstract

In the field of acoustics there is a need to accurately and efficiently simulate the propagation of acoustic waves. Furthermore, as sound generation is a fluid mechanical phenomena, there is a need to study how different flow cases affect sound propagation and generate sound. In order to do this there is a need for a computational fluid dynamics (CFD) method that accurately covers the relevant phenomena.

The lattice-Boltzmann method (LBM) simulates the evolution of particle distributions that can be used to compute the necessary macroscopic field variables. As LBM allows for weak compressibility, it models both acoustic wave propagation and sound generation from fluid-structure interaction without any additions to the original model, which makes it a good simulation tool for these applications.

In this master’s thesis a Python-based code has been developed following the current standard LBM procedures. The models used as well as the code structure and validation tests are described. The results show that although LBM works as a simulation method for Couette flow and monopole sound generation test cases, there is a need to improve several parts of the code in order to be properly accurate for a Poiseuille flow and yield the right frequency response from vortex shedding. It is also concluded that several acoustic phenomena are not yet commonly modeled using LBM and will need future research in order to use LBM to yield more physically accurate results.