The influence of the large-scale vortical structures on the wall shear stress in a circular
impinging jet is investigated experimentally for a Reynolds number of 1260. Time-resolved
particle image velocimetry and polarographic measurements are performed simultaneously.
It is found that the instantaneous wall shear stress is strongly dependent on the vortex
dynamics, particularly for different parts of the transverse vortex. The influence of the vortex
ring, the secondary and tertiary vortices on the ejection/sweep process near the wall is the …