Geometry and scale relationships in high Reynolds number turbulence determined from three-dimensional holographic velocimetry

Abstract

Holographic particle image velocimetry measurements of a fully developed turbulent flow in a square duct (ReH=v̄cH/ν=1.2×105, η=100 μm, Reλ=310) are used for examining the relative alignment between filtered vorticity, strain-rate and subgrid-scale stress tensors. Similar to DNS and previous measurements, the filtered vorticity has a preferred alignment with the intermediate strain-rate eigendirection. Contrary to typical eddy viscosity models, the most compressive strain-rate and most extensive subgrid-scale stress eigendirections have a strongly preferred relative orientation of 34°. The orientations of the other eigendirections are less deterministic and more complex.