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Spatial Distributions of the Axis of Coherent Fine Scale Eddies in Turbulence

Corresponding Author : M. Ashraf Uddin (auddin-mat@sust.edu)

Authors : Mamoru Tanahashi (mtanahas@mes.titech.ac.jp)

Keywords : Computational Fluid Dynamics, Direct Numerical Simulation, Homogeneous Isotropic Turbulence, Coherent Fine Scale Eddy, Intermittency

Abstract :

Spatial distributions of axis of coherent fine scale eddies in turbulence are discussed by using visualization with some physical insights. The axes are determined from DNS data of decaying homogeneous isotropic turbulence up to Reλ =87.9. Visualizations of the axes in the volume unit of integral length scale (lE), Taylor microscale (λ) and Kolmogorov microscale (η) are compared by selecting the visualized width of axes as constant value, square root of Qc * and Qc * , respectively, where Qc * is the second invariant of the velocity gradient tensor. It is shown that the spatial distribution of the fine scale eddies can be characterized by λ and square root of Qc * . The visualization in η unit volume emphasizes that the distribution of the strongest fine scale eddy is more intermittent for high Reλ.  

Published on June 30th, 2014 in Volume 21, Issue 1, Applied Sciences and Technology