Sensitivity analysis of the second and third-order velocity structure functions to the Reynolds number in decaying and forced isotropic turbulence using the EDQNM model
Résumé
Numerical calculations based on a recent version of the eddy-damped quasi-normal model (EDQNM-LMFA) are carried out for homogeneous isotropic turbulence (HIT) with the aim of investigating the dependency on the Reynolds number of second and third order velocity structure functions. The quantities investigated include the energy spectrum , the non-linear energy transfer as well as the second () and third () order moments of the longitudinal velocity increment. Both free decaying HIT and (steady state) forced HIT are considered. The analysis of the structure functions for indicates that, regardless of whether one considers decaying or forced HIT, the large scales affect and in the scaling range. In that range, forcing affects and differently. For forced HIT, exhibits a distinct “bump” near the upper end of the scaling range while no such bump is seen for . The latter quantity remains approximately constant for values of which extend to the scale corresponding to the forcing. For decaying HIT, there is no discernible bump in either or . The slope of in the scaling range approaches the theoretical value of 1, when is sufficiently large. However, at similar , the slope of has not yet reached a constant for either decaying or forced HIT.
Domaines
Physique [physics]
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