Towards aeroacoustic sound generation by flow through porous media

Abstract

In this work, we present single-step aeroacoustic calculations using the Lattice Boltzmann method (LBM). Our application case consists of the prediction of an acoustic field radiating from the outlet of a porous media silencer. It has been proved that the LBM is able to simulate acoustic wave generation and propagation. Our particular aim is to validate the LBM for aeroacoustics in porous media. As a validation case, we consider a spinning vortex pair emitting sound waves as the vortices rotate around a common centre. Non-reflective boundary conditions based on characteristics have been adopted from Navier-Stokes methods and are validated using the time evolution of a Gaussian pulse. We show preliminary results of the flow through the porous medium.

Acoustic multipole sources for the lattice Boltzmann method

“…Because acoustic LB simulations are commonly performed at very low viscosities, i.e., τ close to 1 2 [3,5], the simulations in this article were performed using the regularized collision operator at the inviscid limit τ = 1 2 . The simulations prove that the regularized operator allows stable and accurate zeroviscosity LB simulation of some phenomena, at minimum acoustic generation and propagation.…”

“…In the τ → 1 2 limit, corresponding to the low viscosities commonly chosen for LB acoustics [3,5], this equation is…”

“…It has recently also been applied to practical cases in acoustics [2][3][4] and aeroacoustics [5][6][7].…”

Derivation and analysis of Lattice Boltzmann schemes for the linearized Euler equations

“…In addition, Buick et al [11], Dellar [18], Crouse et al [15], Lallemand and Luo [30] [31], and Marie et al [38] analyzed, tested, and discussed the LBM as tool for acous-tic simulations. Based on the capability of the LBM for complex geometries and acoustics, Hasert et al [21] and Hasert [20] used the LBM enhanced by a sub-grid model to resolve the acoustic field generated by a flow through a porous medium. By using the LBM, they were able to directly simulate the aeroacoustic contributions of the individual pores.…”

Sound Propagation Properties of the Discrete-Velocity Boltzmann Equation

“…However, in the last few years several articles have been published on applying the LBM for computational aeroacoustics (CAA) [3,4], i.e. for simulating generation of sound waves in unsteady flow.…”