Possible modification of the large-scale flow structures by vortical structural interactions

Abstract

We explore the mechanisms behind vortical structural interactions modifying large-scale structures in wall turbulence. The evidence for this in terms of vortex interactions, such as merging and intense vortex strengthening, is found in [4] in ideal flow conditions. Here, these interactions are studied experimentally and numerically in turbulent boundary layer and channel flows respectively. This is done by extracting statistical information from conditional averaging of different events based on the spanwise swirling strength. Experimental results showed vortex merger leading to vortex intensification. This was in good agreement with the results of [4]. However, numerical results did not show complete agreement with experimental results. This may be due to the difference in spatial resolution of experimental and numerical data. Furthermore, the peak Reynolds shear stress did reveal a relative increase in magnitude when two vortices merged in the numerical data. © Published under licence by IOP Publishing Ltd.