Orthogonal Wavelet Analysis of Flow Structures in Asymmetric Wakes

The turbulent wake structures of various scales generated by an asymmetric bluff body have been experimentally investigated in this paper. Firstly, the instantaneous velocity and vorticity of turbulent wake were measured by the high-speed PIV technique at a Reynolds number of 8,960 in the circulating water channel. In order to decompose turbulent structures into a number of subsets based on their central frequencies, one- and two-dimensional wavelet multi-resolution technique is then used to analyze the instantaneous velocity and vorticity. It is found that the large-scale turbulent structure makes the largest contribution to the vorticity and Reynolds shear stresses. However, the small-scale structures make less contribution to the vorticity and Reynolds shear stresses.