DOI: 10.1615/ICHMT.2015.THMT-15
ISBN Print: 978-1-56700-427-4
ISBN CD: 978-1-56700-428-8
On coherent structures in the near field of a pipe jet
要約
We perform a fine-resolved Large-eddy simulation (LES) to study the coherent structures populating the near-nozzle area of a pipe jet at the Reynolds number of 5300. The visualization of the flow shows that the nearwall streaky structures supplied by a pipe flow exist only along the first diameter of the pipe downstream from the nozzle. Interacting with the shear layer the harpin-like structures are generated. Proper orthogonal decomposition (POD) shows that spatial modes corresponding to low azimuthal wavenumbers with |m| ≤ 7 appear to be the most energetic for the first 10 diameters. For a pipe jet the integrated over a cross-section turbulent kinetic energy grows linearly downstream while for a 'top-hat' jet the growth is exponential with the formation of vortex rings. The effect of pipe rotation will be presented in a full paper.