DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf
ISBN Print: 978-1-56700-262-1
ISSN: 2377-2816
Direct measurement of coherent fine scale structure in turbulence by high spatial resolution dual-plane SPIV
SINOPSIS
To investigate fine scale structure of turbulent flows, dual-plane SPIV system was applied to a turbulent jet. This system provides all three velocity components and nine velocity gradients in large measurement region with high spatial resolution (2.8η×2.8η×4.1η), which is same spatial resolution of general direct numerical simulation (DNS). From the velocity gradients, vorticity vectors, second invariant of velocity gradient tensor and energy dissipation rate are obtained exactly. These properties allow an eddy identification which has been used in the analysis of DNS. Velocity distributions on the cross section of the coherent fine scale structure show an elliptic feature. The probability density functions of the diameter and maximum azimuthal velocity of the detected eddies show peaks at D/η ≈ 8 and uθ,max/uk ≈ 1. These characteristics of the fine scale structure coincide with those obtained from DNS.