Riassunto analitico
The present work aims to dynamically establish the role that the inner and the outer cycles have on scalar transport in wall turbulence.
The presented numerical experiments study the evolution of passive scalars driven by velocity fields where inner and outer cycles are alternatively suppressed by using a filtering operation. The cases where inner and outer cycles filters have been applied were compared with the unfiltered one. The flow chosen for this experiment is the zero-pressure gradient temporal boundary layer over a moving flat plate.
The dynamics of the two cycles is found to be relatively independent and autonomous. The outer cycle faces a free boundary at the top and it rescales according to what is supplied by the modified inner cycle.
The inner cycle, on the other hand, resides between the wall and the outer region. As a result, when the outer cycle is suppressed, the scalar fluxes in the outer region decrease and this causes damping in the near-wall region activities.
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