Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-28T03:28:54.910Z Has data issue: false hasContentIssue false
  • English
  • Français

Clarifying Low-Frequency Variatoions Phenomenon Using a Novel Mode Decomposition Method

Published online by Cambridge University Press:  05 May 2011

C.-T. Wang
C.-T. Wang*
Affiliation:
Department of Mechanical Engineering, National I Lan University, I Lan, Taiwan 26047, R.O.C.
*
* Assistant Professor
Get access

Abstract

Low-frequency variations in wake flow are complex and many aspects of its behavior remain poorly understood. A mode decomposition method developed by Huang et al is utilized herein because it can decompose any complicated data set into a finite number of intrinsic modes without distorting their original characteristics. The results of decomposition analysis of the measured base pressure signals reveal that a finite number of various kinds of flow structure modes, with their own characteristic time scales, coexist with the residue that exhibits most of the low-frequency variations in flow at Re = 11760 and 31600, respectively. As the Reynolds number increases, the decomposition method yields more components. Results also show exactly the vortex shedding structure in an intrinsic mode and the low-frequency variations that appear in the residue during vortex shedding process.

Keywords

Low-frequency variationMode decomposition analysis
Type
Articles
Information
Journal of Mechanics , Volume 22 , Issue 3 , September 2006 , pp. 193 - 198
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2006

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1.Bloor, M.S., “The Transition to Turbulence in the Wake of a Circular Cylinder,” J. Fluid Mech., 19, pp. 290–303 (1964).Google Scholar
2.Miau, J. J., Yang, C. C., Chou, J. H. and Lee, K. R., “Suppression of Low-Frequency Variations in Vortex Shedding by a Splitter Plate Behind a Bluff Body,” J. Fluids and Structures, 7, pp. 897–912 (1993).Google Scholar
3.Miau, J. J., Yang, C. C., Chou, J. H. and Lee, K. R., “A T-Shaped Vortex Shedder for a Vortex Flowmeter,” Flow Measurement and Instruments, 4, pp. 259–267 (1993).CrossRefGoogle Scholar
4.Miau, J. J., Wang, J. T., Chou, J. H. and Wei, C. Y., “Characteristics of Low-Frequency Variations Embedded in Vortex Shedding Process,” J. Fluids and Structures, 13, pp. 339–359 (1999).CrossRefGoogle Scholar
5.Williamson, C. H. K., “The Natural and Forced Formation of Spot-Like ‘Vortex Dislocations’ in the Transition of a Wake,” J. Fluid Mech., 243, pp. 393–441 (1992).Google Scholar
6.Williamson, C. H. K., “Three-Dimensional Wake Transition,” J. Fluid Mech., 328, pp. 345–407 (1996).CrossRefGoogle Scholar
7.Eaton, J. K. and Johnston, J. P., “Low Frequency Unsteadiness of a Reattaching Turbulent Shear Layer,” Turbulent Shear Flows Bradbury, L. J. S., Durst, F., Launder, B. E., Schmidt, F. W. and Whitelaw, J. H., Eds., Springer, pp. 162–170 (1982).CrossRefGoogle Scholar
8.Kiya, M. and Sasaki, K., “Structure of Large-Scale Vortices and Unsteady Reverse Flow in the Reattaching Zone of a Turbulent Separation Bubble,” J. Fluid Mech., 154, pp. 463–491 (1985).Google Scholar
9.Szepessy, S., “On the Spanwise Correlation of Vortex Shedding from a Circular Cylinder at High Subcritical Reynolds Number,” Phys. Fluid., 6(7), pp. 2406–2416 (1994).CrossRefGoogle Scholar
10.Najjar, F. M. and Balachandar, S., “Low-Frequency Unsteadiness in the Wake of a Normal Flat Plate,” J. Fluid Mech. 370, pp. 101–147 (1998).CrossRefGoogle Scholar
11.Huang, N.E., Sheng, Z., Long, S. R., Wu, M. C., Shih, H. H., Zheng, Q., Yen, N. C., Tung, C. C. and Liu, H. H., “The Empirical Mode Decomposition and the Hilbert Spectrum for Nonlinear and Non-Stationary Time Series Analysis,” Proc. R. Soc. Lond. A, 454, pp. 903–995 (1998).CrossRefGoogle Scholar
12.Hu, C. C., Miau, J. J. and Chau, J. H., “Instantaneous Vortex-Shedding Behaviour in Periodically Varying Flow,” Proc. R. Soc. Lond. A, 458, pp. 911–932 (2002)Google Scholar
13.Miau, J. J., Wang, J. T., Chou, J. H. and Wei, C. Y., “Low-Frequency Fluctuations in the Near-Wake Region of a Trapezoidal Cylinder with Low Aspect Ratio,” Joural ofFluids and Structures, 17/5, pp. 701–715 (2003).CrossRefGoogle Scholar
14.Kiya, M. and Sasaki, K., “Structure of a Turbulent Separation Bubble,” J. Fluid Mech., 137, pp. 83–113 (1983)Google Scholar