- Volume 20 Issue 4
Analysis of Flow Visualization Results Using Fourier Transform
퓨리에 변환을 활용한 유동 가시화 비교 분석
- Koo, Bon-guk (Department of Naval Architecture and Marine Engineering, Changwon National University) ;
- Park, Jun-mo (School of Electronic and Biomedical Engineering, Tongmyong University) ;
- Kang, Yong-Duck (Department of Naval Architecture and Ocean Engineering, Dong-Eui University)
- Received : 2019.12.09
- Accepted : 2019.12.30
- Published : 2019.12.31
In the boundary layer, vortical system has been analyzed by the statistical methods to identify the vortex interaction. However, there are the limitations in explaining vortices by the mean velocity or the standard deviation. This paper proposed a method to establish a frequency analysis by Fourier transform in order to simultaneously investigate various scale vortices. For this purpose, the flow visualization conducted to reveal a standing vortex, a hairpin vortex and a wake region around a hemisphere attached on a flat plate in a water channel. In addition, the velocity where the hairpin vortex was being generated in the wake region was measured by a hot-film anemometer. To observe changes in the vortex interaction, suction was applied through a hole in front of the hemisphere. For the evaluation of the proposed frequency analysis, the existing statistical results were compared to the frequency analysis that corresponds to the qualitative results of the flow visualization.
Supported by : 창원대학교
- S. J. Kline, W. C. Reynolds, F. A. Schraub, and P. W. Runstadler, "The Structure of Turbulent Boundary Layer,"J. Fluid Mech., vol. 30, pp. 741-773, 1967. https://doi.org/10.1017/S0022112067001740
- M. S. Acarlar and C. R. Smith, Report FM-5, Department of Mechanical Engineering & Mechanics, Lehigh University, USA, 1984.
- Y. G. Guezennec, and H. M. Nagib, "Drag Reduction in Turbulent Boundary Layers," AIAA J., vol. 28, no. 2, pp. 245-262, 1990. https://doi.org/10.2514/3.10381
- Y.-D. Kang, K.-S. Choi, and H. H. Chun, "Direct intervention of hairpin structures for turbulent boundary-layer control," Phys. Fluids, vol. 20, no. 10, pp. 101517-1-101517-13, Oct. 2008. https://doi.org/10.1063/1.3006346
- A. K. Gupta, "Hydrodynamic Modification of the Horseshoe Vortex at a Vertical Pier Junction with Ground," Phys. Fluids, vol. 30, No. 4, pp. 1213-1215, 1987. https://doi.org/10.1063/1.866270
- H. A. Zondag, "The Dynamics of Hairpin Vortices in a Laminar Boundary Layer," PhD dissertation, University of Eindhoven.
- M. S. Acarlar, and C. R. Smith, "A Study of Hairpin Vortices in a Laminar Boundary Layer. Part 1. Hairpin Vortices Generated by a Hemisphere Protuberance," Journal of Fluid Mechanics, vol. 175, pp. 1-41, 1987. https://doi.org/10.1017/S0022112087000272
- S.-Y. Shin, K.-H. Jung, Y.-D. Kang, S.-B. Suh, J. Kim, and N.-H. An, "A Study on the Effect of Large Coherent Structures to the Skin Friction by POD Analysis,' SNAK, vol. 54, no. 5, pp. 406-414, Oct. 2017. https://doi.org/10.3744/SNAK.2017.54.5.406
- J.-B. Lee, M.-H. Kim, and D.-S. Jang,"Feature Extraction in 3-Dimensional Object with Closed-surface using Fourier Transform,"SNAK, vol. 4, no. 3, pp. 21-26, Jul. 2003.