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

Holographic particle image velocimetry measurements of a fully developed tu rbulent flow in a square duct (Re-H=(v) over bar cH/nu=1.2x10(5), eta=100 m u m, Re-lambda=310) are used for examining the relative alignment between f iltered vorticity, strain-rate and subgrid-scale stress tensors. Similar to DNS and previous measurements, the filtered vorticity has a preferred alig nment 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 or ientation of 34 degrees. The orientations of the other eigendirections are less deterministic and more complex. (C) 2000 American Institute of Physics . [S1070-6631(00)02304-7].