Calculation of sound generation and radiation from instationary flows

The Lattice–Boltzmann method (LBM) for simulation of low Mach number flows is evaluated for the application in flow acoustics. By linearization and von-Neumann analysis quantitative measures for the accuracy of phase speed and attenuation of low amplitude sound waves in presence of a mean flow are derived. It is shown that only phase errors are relevant when simulating sound waves in the audible frequency range in air. For the two dimensional 9 bit model and the three dimensional 19 bit model the phase speed error is below 0.1% (1%) as long as the wave is resolved with at least 34 (12) points per wavelength. The LBM is applied to the problem of a Helmholtz resonator under a grazing flow and to the trailing edge noise generation problem. The results clearly demonstrate the ability to reproduce relevant flow acoustic effects.