Resolution of Computational Aeroacoustics Problems on Unstructured Grids with Splitting Method of Low Mach Number Flows

For viscous acoustic computation at low Mach numbers, non-linear incompressible Navier-Stokes equations and acoustic perturbed equations are proposed. The derivation is based on non-linear compressible Navier-Stokes equations. On unstructured collocated grids the flow part and acoustic part are discretized using SIMPLEC method with a cell-centered finite volume method. At the far field boundaries, dispersion-relation-preserving absorbing boundary is applied to handle the outgoing acoustic waves. A viscous acoustic algorithm is proposed to overcome the difficulty. The present method is validated for dipole sound propagation problems at low Mach numbers. Numerical computations of flows past a circular cylinder and flows past a slight shocking circular cylinder shows that the numerical method can be used to simulate of sound propagation in the air.