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A CONJECTURE: TURBULENCE SUBJECTED TO CYCLIC STRAIN ALWAYS DECAYS

I. Hadzic
Dept. of Applied Physics, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands

Kemal Hanjalic
Department of Physics, Novosibirsk State University (NSU), 1, Pirogov Str., Novosibirsk, 630090, Russia; Faculty of Applied Sciences, Delft University of Technology (TU Delft), Building 58, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands

Dominique R. Laurence
Modelling and Simulation Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M13 9PL, UK; EDF R&D, Fluid mechanics, Energy and Environment, 78401 Chatou, France

Abstrakt

Analytical solutions of a second moment closure for homogeneous turbulence subjected to periodic compression-dilatation strains show that both the characteristic turbulence frequency and turbulent kinetic energy eventually decay, irrespective of the initial state. The eddy-viscosity models on the other hand give erroneous results because they overlook the phase lag between periodic strain rate and stresses in the exact production term in the second moment closure. The author's opinion that, turbulence submitted to cyclic strains should always finally decay, remains a conjecture however, since some (justified) simplifications were necessary to produce the analytical solutions.