Direct numerical simulations of axially rotating turbulent pipe flow up to Re_τ = 1000

Direct numerical simulations of axially rotating turbulent pipe flows are conducted for friction Reynolds numbers Re_τ up to 1000 and rotation numbers N = 0-4.0. A non-monotonic trend in friction factor λ is observed at low Re_τ, while at higher Re_τ cases, λ decreases consistently with increasing rotation. New scaling laws and defect laws are proposed for the centerline velocity and mean streamwise velocity, demonstrating improved collapse over existing literature correlations. Rotation modifies the Reynolds stress distribution by suppressing near-wall turbulence while enhancing axial fluctuations in the pipe core. Spectral analysis reveals the emergence of very large-scale motions under rotation, accompanied by an increase in energy at low wavenumbers in both the streamwise and azimuthal directions. These findings highlight the role of rotation in modulating pipe flow turbulence.