Structure identification in pipe flow using proper orthogonal decomposition

• Published in: Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences physical, and engineering sciences, 2017-03, Vol.375 (2089), p.20160086-20160086
• Main Authors: Hellström, Leo H.O., Smits, Alexander J.
• Format: Article
• Language: English
• Subjects: Coherent Structures; Computational fluid dynamics; Computer simulation; Fluid flow; Mathematical models; Pipe flow; Proper Orthogonal Decomposition; Reynolds number; Turbulence; Turbulent flow; Velocity; Velocity distribution; Wall Bounded Flow
• ISSN: 1364-503X; 1471-2962
• DOI: 10.1098/rsta.2016.0086

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’.