Direct numerical simulation of a turbulent pipe flow at high Reynolds number was performed (Ahn et al. 2015). The Reynolds number based on the pipe diameter and bulk mean velocity (\(Re_D\)) was 133000, and the corresponding friction Reynolds number (\(Re_\tau\)) was 3008. The axial domain length was 30R, long enough to fully capture very-large-scale motions and to reduce the influence of the short domain length, where R is the pipe radius. The grid points were 12289×901×3073 along the axial, radial and azimuthal directions, and the corresponding wall-unit resolutions were \({\Delta}x^{+}=7.34\), \({\Delta}r_{min}^{+}=0.36\), \({\Delta}r_{max}^{+}=9.91\), \({\Delta}R\theta^{+}=6.15\). The hybrid parallelization of OpenMP with MPI was adopted to treat the massive memory more than 30 billion grid points. The vortical structures were visualized by the swirling strength (\(\lambda_{ci}\)). The isocontour of \(\lambda_{ci}\) was 6, colored by instantaneous axial velocity.
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