Figure 5

Time series of PIV results at the location of LDA beam crossing using Adaptive Correlation and Adaptive PIV algorithms for the Farfield measurements with a path of close to 2 m. Top panel shows the vertical velocity inferred from Adaptive Correlation using a fixed interrogation area of 16 × 16 pixels at highest optical turbulence, ΔT = 13 °C. There is significant noise in the PIV signal, due to the optical turbulence effect of smearing and defocusing the PIV particles. Middle and bottom panels are also for highest optical turbulence, ΔT = 13 °C, but using a fixed interrogation area of 64 × 64 pixel for the middle panel and, in the bottom panel, inferred with the Adaptive PIV algorithm, which varies the interrogation area depending on particle concentration and velocity gradients.