2003 Volume 46 Issue 3 Pages 366-376
The near wake generated by a triangular cylinder and a screen, respectively, has been investigated with a view to provide information on the effect of initial conditions on turbulence structures of various scales based on the wavelet multi-resolution analysis. The velocity data were simultaneously obtained at x/h (x is the streamwise distance downstream of the wake generator and h is the height of the wake generator)=20 using a rake of eight X-wires aligned in the plane of mean shear. A vector wavelet multi-resolution technique was applied to decompose the velocity data into a number of wavelet components based on the central frequencies. The instantaneous sectional streamlines and vorticity field were used to reveal the turbulent structures at each wavelet component/central frequency. It was found that the behavior of large- and intermediate-scale structures depend on the initial conditions and the small-scale structures are independent of the initial conditions. The contributions from the wavelet components to the time-averaged Reynolds stresses and vorticity variance were estimated. Both the large-scale and intermediate longitudinal structures make the most significant contributions to Reynolds stresses in the triangular cylinder wake, but the contribution from the large-scale structures appears dominating in the screen wake. The relatively small-scale structures of the triangular cylinder wake contribute most to the total spanwise vorticity variance.
JSME international journal. Ser. 1, Solid mechanics, strength of materials
JSME international journal. Ser. A, Mechanics and material engineering
JSME international journal. Ser. 3, Vibration, control engineering, engineering for industry
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JSME International Journal Series A Solid Mechanics and Material Engineering