Effect of initial condition on the sound generation by flow past a rotary-oscillating circular cylinder

Effects of forced rotary oscillation on the generation of the sound from a circular cylinder in a uniform flow are investigated by direct solution of the two-dimensional, unsteady, compressible Navier-Stokes equations. Results show that the effect on the sound generation of rotary oscillation with frequency f is equivalent to that of periodic blowing and suction with frequency 2f; the sound field is determined by the interaction between the monopole generated by rotary oscillation and the dipole generated by vortex shedding from the cylinder. Results also show that, depending on initial conditions, different sound fields as well as flow fields can be generated for same flow parameters. (c) 2006 American Institute of Physics.