Small-scale statistics in direct numerical simulation of turbulent channel flow at high-Reynolds number

Small-scale statistics in turbulent channel flow are studied by high resolution direct numerical simulations with the friction Reynolds number up to Re τ = 2560. The second order velocity statistics in the inertial subrange of the log-low region are found to be not far from those predicted by Kolmogorov's universal equilibrium theory, although the agreement is not perfect. The shear parameter S * decreases with the distance y + from the wall and S * ≲ 0.1 in y + > 400 for large Re τ , where S * is the ratio of the Kolmogorov time scale to the mean shear time scale. For larger Re τ , the y + -dependence of S * is closer to a simple theoretical estimate in the log-low region.