On the vorticity-generated sound for moving surfaces

A formulation for analyzing the mechanism of vorticity-generated sound is presented, which is based upon an extension of a boundary integral equation method for unsteady quasi-potential compressible flows. The extension is obtained through an exact decomposition of the velocity field into potential and rotational contributions, with the distinguishing feature that the vortical contribution vanishes in much of the field. The novelty is that the construction of the vortical contribution of the velocity is such that discontinuities across the wake of the two (potential and rotational) contributions are eliminated, thereby facilitating possible implementations.