Statistical Properties of High-Reynolds Number Turbulent Flow Fields : 2nd Report, Measurement of Three-Dimentional Energy Spectra

Abstract

Three-dimensional energy and dissipation spectra were experimentally obtained in a large-scale turbulence field. The characteristic scales of turbulent eddies, the energy-containing eddy, l_o, the largest locally isotropic eddy, l_G, and the eddy of maximum dissipation, l_D, were determined in the spectral profile. The energy spectrum became self-similar for k>1/l_G but the l_o scale was reduced in accordance with the streamwise decay of the turbulence energy. The l_D scale was proven to be more appropriate as the scale of the energy-dissipative eddy than the Taylor microscale, λ. The energy spectrum started to depart from Kolmogorov's -5/3 low at η/l_D∼0.15 and was most accurately approximated by the theoretical profiles with an exponential tail in the far dissipation range.