Wavelet analysis of coherent structures in a three-dimensional mixing layer |
| |
Authors: | Lin Jianzhong Shao Xueming Ni Limin |
| |
Institution: | (1) Department of Mechanics, State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, 310027 Hangzhou, China |
| |
Abstract: | Wavelet analysis is applied to the results obtained by the direct numerical simulation of a three-dimensional (3D) mixing
layer in order to investigate coherent structures in dimension of scale. First, 3D orthonormal wavelet bases are constructed,
and the corresponding decomposition algorithm is developed. Then the Navier-Stokes equations are transformed into the wavelet
space and the architecture for multi-scale analysis is established. From this architecture, the coarse field images in different
scales are obtained and some local statistical quantities are calculated. The results show that, with the development of a
mixing layer, the energy spectrum densities for different wavenumbers increase and the energy is transferred from the average
flow to vortex structures in different scales. Due to the non-linear interactions between different scales, cascade processes
of energy are very complex. Because vortices always roll and pair at special areas, for a definite scale, the energy is obtained
from other scales at some areas while it is transferred to other scales at other areas. In addition, energy dissipation and
transfer always occur where an intense interaction between vortices exists.
The project supported by the Research Fund for the Doctoral Program of Higher Education and the National Natural Science Foundation
for Outstanding Youth of China (19925210) |
| |
Keywords: | wavelet transforms numerical simulation mixing layer coherent structure |
本文献已被 SpringerLink 等数据库收录! |
|