Transmission of sound through a single vortex

We investigate experimentally the deformation of acoustic wavefronts after crossing of a single, isolated vortex in free space. The incident sound wavelength can be varied in a large domain. We study the wavefronts at variable distance after transmission through the vortex, when the wavelength and the vortex strength are varied. For small wavelength (lambda<<a, the vortex core size) our results are in very good agreement with predictions and simulations based on geometrical acoustics principles. However, as the sound wavelength increases to value comparable with the vortex diameter, the deformation of the wavefronts show the development of scattering contributions, with characteristics in agreement with recent theoretical and numerical studies.