Nature of Turbulence in Wall -Bounded Flows

168 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.Particle-image velocimetry measurements inside a fully transpired channel flow apparatus with side-wall injection are used to determine the role of side-wall injection length scale on core turbulence. Smaller pore sizes create laminar flow near the head end of the channel while the larger pore sizes induce transition to turbulence at the head end itself. Flow visualization studies are used to identify persistent axial and spanwise vortices in the flow. The vortices swept by the mean velocity affect the injection velocity streamlines that emerge out of the pores creating injection-velocity fluctuations, that are amplified by the mean strain field to create Reynolds shear stress downstream. Perturbations of the Taylor-Culick solution are numerically computed to demonstrate the amplification of axial and azimuthal vorticity.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD