Velocity of line plumes on the hot plate in turbulent natural convection

We measure the velocity field in a horizontal field near the hot plate in turbulent convection using stereo PIV for 106 < Raw < 109 and 5.2 < Pr < 4.We then extract the line plumes from this velocity field using a divergence criterion using the PIV technique on the obtained plume structures, which gives us the velocity field of the plume motion. The statistical analysis of this velocity field of the plumemotion shows the coexistence of two different kinds of motion of the plumes, lateral merging and motion along the plumes.