Direct aeroacoustic simulation with a cumulant Lattice-Boltzmann model
Claus Feuchter
Abstract
This study presents a direct aeroacoustic simulation using a cumulant lattice Boltzmann method that provides very high stability without modifying the bulk viscosity compared to the Bhatnagar–Gross–Krook model. It is shown with the Chapman–Enskog analysis that the numerical model recovers the compressible Navier–Stokes equations for low Mach number flows to second-order accuracy. The low dissipation and low dispersion properties required for aeroacoustics are verified by simulating a planar wave propagation test case. The predictive accuracy of the method is investigated for a complex test case by performing a direct aeroacoustic simulation for a highly turbulent flow in a channel with obstructive walls and an orifice leading the flow into an ambient environment. The acoustic sound pressure level is evaluated for microphone positions inside the turbulent flow where flow induced sources are located, and also for positions in the far field of the channel orifice. The agreement between simulation results of the cumulant lattice Boltzmann method and experimental data is excellent. The simulation predicts for all microphone positions the measured spectra over a wide frequency range and single dominant peaks are captured very well.