• Dr. Philippe Lavoie
  • University of Toronto
  • 104D Surge Building
  • 4:00 p.m.
  • Faculty Host: Dr. William Devenport

Recent work behind square-fractal grids has sparked renewed interest in canonical grid turbulence.  This renewed interest is partly due to a number of unexpected properties.  For example, measurements downstream of a square-fractal geometry showed turbulence that decays at an accelerated rate compared to traditional grid turbulence experiments.  Furthermore, the turbulence generated by square-fractals did not obey the expected scaling of the turbulence kinetic energy dissipation rate. In this talk, we will present measurements over an extended downstream region using a square-fractal-element grid, composed of a 12 by 8 pattern of square fractal elements mounted to a background mesh. This allows for observations to be made farther downstream relative to the largest element in the grid geometry, than previous studies. These measurements will be compared to the turbulence downstream of classical grids with similar geometric characteristics measured in the same facility. Additionally measurements made behind a new active grid are also considered. Our measurements unambiguously reconcile the differences previously reported between fractal and classical grid turbulence, thus settling some fundamental questions that had recently been raised in the literature.

Biography:

Dr. Philippe Lavoie is an Associate Professor at the University of Toronto Institute for Aerospace Studies (UTIAS) and the Associate Director for the Center for Research in Sustainable Aviation based at UTIAS. His research areas include turbulence, flow control and experimental aerodynamics. His current research is focused on studying flow structures and instabilities associated with transitional and turbulent flows as a precursor to their control, as well as the implementation of modern active flow control techniques to improve the characteristics of these phenomena. His research on fundamental turbulence includes experimental studies using grid-generated turbulence and round turbulent jets.