Implementation of Direct Acoustic Simulation using ANSYS Fluent

Direct Acoustic Simulation (DAS) is a powerful Computational Aero-Acoustics method that obtains hydrodynamic and acoustic solutions simultaneously by solving compressible Navier-Stokes equation together with state equation of ideal gas. Thus, DAS has advantages for cases with flow-acoustic coupling and high Mach numbers (Ma). With an increasing demand of massive-scale calculations, a robust numerical solver for DAS is required. ANSYS Fluent is a suitable CFD platform with proven robustness. However, there is no direct implementation of DAS in the current version of ANSYS Fluent. The present study, therefore, aims to investigate an approach for implementing DAS using ANSYS Fluent. Given the acoustic part of fluctuations is much smaller than the hydrodynamic part in amplitudes, a DAS solver requires high accuracy and low dissipation. Based on these needs, proper solution methods, spatial-discrete methods and boundary conditions are firstly determined through simple calculations of two-dimensional propagating plane waves. Afterwards, aeroacoustics of a two-dimensional cavity flow at Ma = 0.6 is calculated to verify the capability for solving separating flow with the aforementioned set-up. Finally, aeroacoustics of a cylindrical bluff body at a turbulent regime and Ma = 0.2 is calculated in three-dimensions to verify the capability for solving turbulent flow using Monotonically Integrated Large Eddy Simulation.