Energy-based characterisation of large-scale coherent structures in turbulent pipe flows.

The article delves into the analysis of large-scale coherent structures in turbulent pipe flows at different Reynolds numbers. By utilizing the Karhunen-Loève decomposition and a unique Voronoi diagram method, the research identifies two categories of structures - wall-attached and detached eddies - based on their characteristics and energy contributions. The study demonstrates that as the Reynolds number increases, the energy distribution of these structures changes, with attached eddies scaling linearly with the wall-normal distance while detached eddies maintain a consistent size. This research sheds light on the spatial distribution of these structures, potentially aiding in understanding the variations in mean velocity between pipe and channel flows and enhancing the modeling of large-scale motions. [Extracted from the article]