Large-scale influences in near-wall turbulence.
Hot-wire data acquired in a high Reynolds number facility are used to illustrate the need for adequate scale separation when considering the coherent structure in wall-bounded turbulence. It is found that a large-scale motion in the log region becomes increasingly comparable in energy to the near-wall cycle as the Reynolds number increases. Through decomposition of fluctuating velocity signals, it is shown that this large-scale motion has a distinct modulating influence on the small-scale energy (akin to amplitude modulation). Reassessment of DNS data, in light of these results, shows similar trends, with the rate and intensity of production due to the near-wall cycle subject to a modulating influence from the largest-scale motions.
Hutchins
Nicholas
N
Walter Bassett Aerodynamics Laboratory, Mechanical and Manufacturing Engineering, University of Melbourne, Victoria 3010, Australia. nhu@unimelb.edu.au
Marusic
Ivan
I