SPECTRAL-ANALYSIS OF THE VONKARMAN FLOW USING ULTRASOUND SCATTERING

We report experimental evidence that the scattering of sound waves by a fluid flow may be used, as a nonintrusive and nonlocal method, to characterize the space-time structure of the flow. The experiment has been performed using, as a test flow, the von Karman vortex street behind a cylinder at a low Reynolds number (Re = 50). The results are in good qualitative agreement with earlier experiments on the von Karman vortex street and with recent theoretical developments on sound-velocity interaction.