Acoustic radiation frequency of a cylindrical vortex

Acoustic radiation frequency of a cylindrical vortex in the air has been calculated. Calculations are based on the Navier-Stokes equations using the expansion of the functions in powers of small parameter characterizing the initial vorticity. Non-uniform system of parabolic differential equations with constant coefficients is obtained. The initial radius of the cylinder varies over a wide range. The problem is considered for the case of plane flow. In contrast to previously results, it is shown that at small values of vorticity, the frequency of the acoustic radiation depends only on the geometric size (the initial radius of the vortex).