Figure 7.
Forward jet with vortex case. Detail of the upstream vortex for forward jet flow over a fence with upstream vortex case. Black vector arrows represent PTV-derived velocity field data, and grey vector arrows represent combined PIV and PTV data. (a) Velocity vector field. (b,c) Velocity vector field with overlaid vorticity and pressure fields. The scale bar in (a) represents a distance of 0.1 mm, and the scale arrow represents a flow speed of 1 m s−1. (d–f) Profiles of polar velocity components, vorticity and pressure along the transect indicated by the dashed lines in (a–c). The transect starts at the scale surface and runs through the vortex centre (yellow circle in (a–c), vertical dashed line in (d–f)). The low-pressure region above the scale (c,f) is likely responsible for the scale bristling in the absence of flow reversal.