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Scalings of the outer energy source of wall-turbulence

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By means of the multidimensional description given by the Kolmogorov equation we study the energy transfer physics and the production mechanisms of wall-turbulent flows at moderately high Reynolds numbers. Two driving mechanisms are identified for the energy fluxes. The first stronger one, here called driving scale-range (DSR), belongs to the near-wall cycle. As expected, its topology remains unaltered with Reynolds number while its intensity is found to slightly increase with Re. The second mechanism, here called outer scale-range (OSR), takes place in the overlap layer and highlights different features in agreement with the attached eddies hypothesis usually considered to describe the overlap dynamics.

Author(s):

Andrea Cimarelli    
Department of Industrial Engineering, DIN, Alma Mater Studiorum, University of Bologna
Italy

Elisabetta De Angelis    
Department of Industrial Engineering, DIN, Alma Mater Studiorum, University of Bologna
Italy

Philipp Schlatter    
Linné FLOW Centre, KTH Mechanics, Stockholm
Sweden

Geert Brethouwer    
Linné FLOW Centre, KTH Mechanics, Stockholm
Sweden

Alessandro Talamelli    
Department of Industrial Engineering, DIN, Alma Mater Studiorum, University of Bologna
Italy

Carlo Massimo Casciola    
Dipartimento di Ingegneria Meccanica e Aerospaziale, Università di Roma La Sapienza
Italy