Wavelet multiresolution analysis of stereoscopic particle-image-velocimetry measurements in lobed jet

Li, H.; Hu, H.; Kobayashi, T.; Saga, T.; Taniguchi, N.

doi:10.2514/3.15160

Cited by 6 publications

(6 citation statements)

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“…Some of the early attempts include those on elliptic and rectangular jets. These include some analytical (Crighton 1973), numerical (Morris 1988;Tam & Thies 1993;Baty & Morris 1995) and some relevant experimental studies focusing on the turbulence, mixing and acoustics of non-axisymmetric jets (Tam & Zaman 2000;Li et al 2002;Zaman et al 2003;Miao et al 2015;Li et al 2001Li et al , 2002Hu et al 2002). The analytical work of Crighton (1973) showed that separable solutions can be obtained for elliptic jets.…”

Section: Introductionmentioning

confidence: 99%

Temporal stability analysis of jets of lobed geometry

Lyu

Dowling

2018

J. Fluid Mech.

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A 2D temporal incompressible stability analysis is carried out for lobed jets. The jet base flow is assumed to be parallel and of a vortex-sheet type. The eigenfunctions of this simplified stability problem are expanded using the eigenfunctions of a round jet.The original problem is then formulated as an innovative matrix eigenvalue problem, which can be solved in a very robust and efficient manner. The results show that the lobed geometry changes both the convection velocity and temporal growth rate of the instability waves. However, different modes are affected differently. In particular, mode 0 is not sensitive to the geometry changes, while modes of higher-orders can be changed significantly. The changes become more pronounced as the number of lobes N and the penetration ratio ǫ increase. Moreover, the lobed geometry can cause a previously degenerate eigenvalue (λ n = λ −n ) to become non-degenerate (λ n = λ −n ) and lead to opposite changes to the stability characteristics of the corresponding symmetric (n) and antisymmetric (−n) modes. It is also shown that each eigen-mode changes its shape in response to the lobes of the vortex sheet, and the degeneracy of an eigenvalue occurs when the vortex sheet has more symmetric planes than the corresponding mode shape (including both symmetric and antisymmetric planes). The new approach developed in this paper can be used to study the stability characteristics of jets of other arbitrary geometries in a robust and efficient manner.

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Section: Introductionmentioning

confidence: 99%

Temporal stability analysis of jets of lobed geometry

Lyu

Dowling

2018

J. Fluid Mech.

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“…To extract various scales in turbulent structures, the wavelet multi-resolution analysis is used to decompose the velocity fluctuation components u j into a number of orthonormal wavelet components based on wavelet levels, which correspond to the different central frequencies and are directly linked to turbulent structure scales (17) - (21) . The wavelet multi-resolution analysis may process fewer data by selecting relevant details that are essential to perform the extraction of multi-scale flow structures, and decompose the velocity fluctuations both in Fourier and physical spaces.…”

Section: Wavelet Multi-resolution Analysismentioning

confidence: 99%

Orthogonal Wavelet-Decomposed 3-D Vorticity of a Turbulent Cylinder Wake

Rinoshika

Zhou

2006

JSME international journal. Ser. B, Fluids and thermal engineer

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A wavelet multi-resolution technique is applied to analyze the three vorticity components obtained simultaneously using an eight-wire probe in the far wake of a circular cylinder at a Reynolds number of 6 000. Using this technique, the vorticity is decomposed into a number of orthogonal wavelet components based on different central frequencies, which correspond to the scales of turbulent structures. The vortical structure of each wavelet component is examined in terms of vorticity variance. The present result shows a relatively large contribution to the longitudinal vorticity variance from the large-scale structures than both to the transverse and to the spanwise vorticity components. The dominant contributions to the vorticity variances are from the intermediate and relatively small-scale structures.

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“…Ko et al 11) employed a waveletbased multi-resolution method to enhance spatial resolution of PIV. Li et al 12) recently developed a wavelet-based vector multi-resolution technique for a high-resolution stereoscopic PIV system that reveals information on the threedimensional multi-scale structure features of lobed jet mixing flow.…”

Section: Introductionmentioning

confidence: 99%

Application of Wavelet Technique to False Vector Correction and Data Compression in PIV.

2003

Trans. Japan Soc. Aero. S Sci.

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A wavelet-based vector compression technique was proposed as a new technique of PIV post-processing for efficiently eliminating erroneous vectors and reducing physical storage. To determine the effect of the choice of wavelet bases, the velocity vector field obtained from standard PIV images was compressed using some known wavelet functions, such as Daubechies, Coifman and Baylkin families. It was found that the lower-order wavelet bases provide good compression performance because they have good physical localization, which in turn, increases energy compaction. When being applied to the PIV result of a jet, the correction of erroneous vectors can be realized by increasing the compression ratio to 16.

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Wavelet multiresolution analysis of stereoscopic particle-image-velocimetry measurements in lobed jet

Cited by 6 publications

References 0 publications

Temporal stability analysis of jets of lobed geometry

Temporal stability analysis of jets of lobed geometry

Orthogonal Wavelet-Decomposed 3-D Vorticity of a Turbulent Cylinder Wake

Application of Wavelet Technique to False Vector Correction and Data Compression in PIV.

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