Sound generation due to a spinning vortex pair near the flat and curved wall

A numerical study of a two-dimensional acoustic field is carried out for a spinning vortex pair located near a wall to investigate the effect of the wall from the spinning quadrupole source in unsteady vortical flows. Based on the unsteady hydrodynamic information from the known incompressible flow field, the perturbed compressible acoustic terms derived from the Euler equations are calculated. Non-reflecting boundary conditions on the free field and the solid boundary conditions are developed for a generalized curvilinear coordinates system to investigate the effect of a curved wall. It is concluded that the sound generated by the quadrupole sources of unsteady vortical flows in the presence of a flat wall or a circular cylinder can be calculated by using the source terms of hydrodynamic flow fluctuations in both near and far acoustic fields simultaneously.