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Published on: July 19, 2016
Wavelet multiresolution analysis of the three vorticity components in a turbulent far wake
1School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798. mtmzhou@ntu.edu.sg
Summary
Turbulent far wake analysis reveals intermediate and small-scale structures dominate vorticity variances. Higher Reynolds numbers decrease large-scale contributions, while small-scale contributions significantly increase between Reynolds numbers 2000 and 4000.
Area of Science:
- Fluid Dynamics
- Turbulence Research
- Wavelet Analysis
Background:
- Turbulent wakes are complex fluid phenomena.
- Understanding vortical structures is crucial for predicting wake behavior.
- Previous studies indicated changes in small-scale structure generation around Reynolds number 5000.
Purpose of the Study:
- To characterize vortical structures in a turbulent far wake.
- To analyze the contribution of different scales to vorticity variances.
- To investigate the influence of Reynolds number on these structures.
Main Methods:
- Wavelet multiresolution technique applied to vorticity decomposition.
- Simultaneous measurement of three vorticity components using an eight-wire probe.
- Experiments conducted at Reynolds numbers 2000, 4000, and 6000.
Main Results:
- Dominant contributions to vorticity variances originate from intermediate and small-scale structures.
- Contributions from large and intermediate scales decrease as Reynolds number increases.
- A significant jump in small-scale structure contributions occurs between Reynolds numbers 2000 and 4000.
Conclusions:
- Turbulence exhibits memory, with past states influencing current dynamics.
- The findings support the concept of turbulence remembering its origin.
- Scale interactions in turbulent wakes are Reynolds number dependent.
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