The measurement of flow velocity and acoustic particle velocity using particle-image velocimetry

This paper outlines the method by which the flow velocity and acoustic particle velocity can be measured instantaneously over an area using particle-image velocimetry techniques. Theoretical expressions for the power spectrum and autocorrelation function of the intensity distribution in the plane of the interrogation area when a flow and sound field is present are derived and it is shown that the flow velocity and the acoustic particle velocity can be measured. The technique is used to measure the velocities in a standing wave tube with a monotonic sound field of sufficient strength such that acoustic streaming is set up. The limitations of this technique are also discussed.