Abstract
Direct numerical simulations of Taylor-Couette flow from Re = 8000 to 25 000 have been performed to understand the spectral characteristics of turbulence in the transition of the Reynolds number dependency of the mean torque near Re = 10 000. The velocity fluctuations are decomposed into the wavenumber components, and their contributions in the radial profiles of the Reynolds stress and the transmission of the mean torque are evaluated. In the net mean torque, the contribution of the azimuthally averaged component overtakes that of the remaining turbulent counterparts around Re = 15 000. Therefore, the torque transition can be explained by the competition between the contributions of azimuthally averaged Taylor vortex and the remaining turbulent fluctuations.
