Characterization of very-large-scale motions in high-Re pipe flows Articles uri icon

publication date

  • June 2019

start page

  • 1

end page

  • 8

volume

  • 104

International Standard Serial Number (ISSN)

  • 0894-1777

Electronic International Standard Serial Number (EISSN)

  • 1879-2286

abstract

  • Very-large-scale structures in pipe flows are characterized using an extended Proper Orthogonal Decomposition (POD)-based estimation. Synchronized non-time-resolved Particle Image Velocimetry (PIV) and time-resolved, multi-point hot-wire measurements are integrated for the estimation of turbulent structures in a pipe flow at friction Reynolds numbers of 9500 and 20000. This technique enhances the temporal resolution of PIV, thus providing a time-resolved description of the dynamics of the large-scale motions. The experiments are carried out in the CICLoPE facility. A novel criterion for the statistical characterization of the large-scale motions is introduced, based on the time-resolved dynamically-estimated POD time coefficients. It is shown that high-momentum events are less persistent than low-momentum events, and tend to occur closer to the wall. These differences are further enhanced with increasing Reynolds number.

keywords

  • pipe flow; boundary layer; pod; very-large-scale motions