Universality of the Kolmogorov constant in numerical simulations of turbulence

Motivated by a recent survey of experimental data [K. R, Sreenivasan, Phys. Fluids 7, 2778 (1995)], we examine data on the Kolmogorov spectrum constant in numerical simulations of isotropic turbulence, using results both from previous studies and from new direct numerical simulations over a range of Reynolds numbers (up to 240 on the Taylor scale) at grid resolutions up to 512 degrees. It is noted that in addition to k(-5/3) scaling, identification of a true inertial range requires spectral isotropy in the same wave-number range. The new simulations indicate approximate inertial range behavior at lower wave numbers than previously thought, with proportionality constants C-1, and C in the one-and three-dimensional energy spectra, retrospectively, about 0,60 and 1.62. The latter suggests C-1 approximate to 0.53, in excellent agreement with experiments. However, the one-and three-dimensional estimates are not fully consistent, because of departures (due to numerical and statistical limitations) from isotropy of the computed spectra at low wave numbers, The inertial scaling of structure functions in physical space is briefly addressed.