Particle image velocimetry applied to a stirred vessel

Flow in a stirred vessel was investigated using a scanning particle image velocimetry (PIV) system that interrogated the vessel from different aspects using automated placement of camera and light plane. PIV revealed the u, u, and w components in three-dimensional space for the time-averaged velocity vectors and the standard deviation of the fluctuations throughout a vessel that contained a very turbulent flow. Directional ambiguity, intrinsic to elementary PIV, was avoided by using an asymmetric illumination function. Additional processing applied to the velocity vectors exposed the circulation patterns throughout the vessel, including zones surrounding the baffles, impeller, and shaft. The regional variation in mixing rate indicated by PIV agreed with direct measurement of the mixing rate.