Structure identification in pipe flow using proper orthogonal decomposition.
The energetic motions in direct numerical simulations of turbulent pipe flow at Reτ=685 are investigated using proper orthogonal decomposition. The procedure is extended such that a pressure component is identified in addition to the three-component velocity field for each mode. The pressure component of the modes is shown to align with the streamwise velocity component associated with the large-scale motions, where positive pressure coincides with positive streamwise velocity, and vice versa. The streamwise evolution of structures is then visualized using a conditional mode, which exhibit a strong similarity to the large-scale, low-momentum motions. A low-pressure region is present in the downstream section of the structure, and a high-pressure region is present in the upstream section.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'.
Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA lhellstr@princeton.edu.
Leo H O
http://orcid.org/0000-0002-1773-8875
LH
Hellström
Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA.
Alexander J
http://orcid.org/0000-0002-3883-8648
AJ
Smits
coherent structures; turbulence; wall bounded flow