Eulerian and Lagrangian insights into a turbulent boundary layer flow using time resolved tomographic PIV

Turbulent boundary layer (TBL) flow consists of manifold temporal and spatial scales and is governed by the organization and decay of self-sustaining coherent flow structures driven by entrained high momentum fluid. Generic flow structures such as hairpin-like vortices and spanwise alternating wall bounded low- and high-speed streaks have been observed and extensively analyzed with both experimental and numerical methods. The role of these structures for the wall normal and spanwise fluid exchange has been highlighted mostly within an Eulerian reference frame. But for an understanding of the momentum exchange in turbulent wall flows a step towards a spatially resolved Lagrangian frame of reference would be advantageous. The data achieved from the present application of time-resolved tomographic PIV to a flat plate turbulent boundary layer flow enables for the first time the investigation of the flow structures and related particle motions within a temporally and spatially resolved Lagrangian and Eulerian frame of reference