Fig. 3

Raw and post-processed \(\mu\)PIV results for cases A and D. (a, c) Representative instantaneous \(\mu\)PIV raw images for cases A and D, respectively, and (b, d) corresponding time-averaged velocity fields obtained via cross-correlation at \(z/D_h \approx 0.16\). Results are obtained by averaging a \(64 \times 64\) pixel interrogation window with \(50\%\) overlap over 200 images (100 pairs). The magenta curves correspond to the normalized time-averaged streamwise velocity profiles, while the yellow lines indicate the upper and lower boundaries of the microchannel corresponding to the lateral walls.