Identification and analysis of the meandering of a fin-tip vortex using Proper Orthogonal Decomposition (POD)
| Autor: | Soon-Kong Lee, Peter Manovski, Chetan Kumar, Matteo Giacobello, Yunpeng Xue |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Fluid Flow and Transfer Processes
Physics Turbulence Mechanical Engineering 02 engineering and technology Mechanics Condensed Matter Physics 01 natural sciences 010305 fluids & plasmas Vortex Stereoscopic particle image velocimetry Physics::Fluid Dynamics 020303 mechanical engineering & transports Point of delivery 0203 mechanical engineering Condensed Matter::Superconductivity 0103 physical sciences Turbulence kinetic energy Proper orthogonal decomposition Vector field Eigenvalues and eigenvectors |
| Zdroj: | International Journal of Heat and Fluid Flow. 82:108556 |
| ISSN: | 0142-727X |
| DOI: | 10.1016/j.ijheatfluidflow.2020.108556 |
| Popis: | The meandering of a vortex exists in a broad range of engineering applications and can lead to flow instability and other undesirable characteristics. Compared to a static vortex, measurement of a meandering vortex can result in a ‘smeared’ mean-flow field and increased levels of turbulence at the centre of the vortex. A case study was performed here on the meandering nature of a fin-tip vortex generated by a manoeuvring submarine. From stereoscopic particle image velocimetry (SPIV) measurements, it is possible to remove the meandering by shifting each instantaneous velocity field so as to produce a common centre for the vortex. In this paper, a snapshot Proper Orthogonal Decomposition (POD) technique is used to capture the dominant large-scale coherent structures (from inspection of eigenvalue or energy distributions) and to improve vortex centre identification. The POD reconstructed velocity field using only the most energetic modes enabled the coherent structures of the flow to be clearly visualised, providing improved identification of the vortex centre and subsequent evaluation of the meandering effect on the turbulent statistics. The present findings suggest that the vortex meandering only has a small impact on the ensemble-averaged resultant velocity, while contributing up to a maximum of 28% for the fluctuating component. The meandering correction also leads to an overall decrease of turbulence intensity in the peak fluctuating region of the vortex core. |
| Databáze: | OpenAIRE |
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