Turbulent Boundary Layers

• two-dimensional, zero-pressure gradient turbulent boundary layer
• two-dimensional turbulent boundary layer over a bump
• three-dimensional turbulent boundary layer over a bump
• turbulent flow over a rotating disk

Two-dimensional, zero-pressure gradient turbulent boundary layer:

• Velocity isosurfaces.
  Shown in the figure is a three-dimensional perspective of velocity isosurfaces in a spatially developing turbulent boundary layer.  The calculation was performed using Large Eddy Simulation in which a recycling/rescaling procedure is used to generate the inflow condition. The method for generating the inflow signal is described in Lund, Wu and Squires (1998).

Two-dimensional turbulent boundary layer over a bump:

• The following visualizations are from Large Eddy Simulations and Reynolds-averaged Navier-Stokes calculations of a statistically two-dimensional boundary layer flowing over a bump.  A canonical turbulent boundary layer at momentum thickness Reynolds number 1500 is introduced approximately five bump heights upstream of the leading edge of the bump. The flow is then subject to alternating signs in streamwise pressure gradient and surface curvature.

streamwise velocity contours,  Re_q= 1500 at the inlet, direct resolution of the wall layer in LES.

streamwise and vertical velocity contours, Re_q= 1500 at the inlet, RANS using v²-f model

kinetic energy and v^2 contours, Re_q= 1500 at the inlet, RANS using v²-f model

Three-dimensional turbulent boundary layer over a bump

• The following visualizations are from Large Eddy Simulations of the three-dimensional turbulent boundary layer which forms as two-dimensional boundary layer flows over a swept bump.  A canonical turbulent boundary layer at momentum thickness Reynolds number 1500 is introduced approximately six bump heights upstream of the leading edge of the bump, the bump is swept at 45 degrees with respect to the upstream flow.. The flow is subject to alternating signs in streamwise and spanwise pressure gradients and surface curvature.

near-wall particle traces,  Re_q= 1500 at the inlet, direct resolution of the wall layer

velocity isosurfaces,  Re_q= 1500 at the inlet, direct resolution of the wall layer

near-wall particle traces,  Re_q= 3800 at the inlet, modeled wall layer.  Particle traces are drawn in a plane at a wall-normal position approximately five percent of the boundary layer thickness