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Keywords: proper orthogonal decomposition, dynamic mode decomposition, velocity field, surface pressure, span-wise correlation, aerodynamic force, bluff body, particle image velocimetry.

Summary

In this study, surface pressure and velocity field near the leading edge of a flat rectangular prism with a chord/depth ratio of 8.0 are measured in order to discuss the mechanism of correlation increase of flow near the prism and resulting surface pressure along a span-wise direction. The flow field is visualized then converted to a velocity vector field using a particle image velocimetry (PIV) technique, and the velocity vector space is decomposed using two different methods, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). The prism is set in still conditions in the turbulence grid of the wind tunnel. A two dimensional flow field in a plane (xy and xz planes, x: chord-wise, y: span-wise, z: vertical (normal to side surface) directions) is visualized using laser sheet and smoke generator. Surface pressure correlation between at the reference point near the leading edge and at the other point demonstrates a more correlated tendency if these two points are located along a line which has skew angle to the main flow direction. As for the mode decomposition of velocity field near the leading edge, some POD modes indicate non-uniform shape along span-wise direction. Particularly in some of the non-uniform modes for u and v in xy plane, there is a ridge in its mode shape with a skew angle to the main flow direction. This implies the cross momentum transport, which means the transport of u-momentum towards the span-wise direction by the v-component and of the v-momentum towards a chord-wise direction by the u-component, respectively. This may create higher correlation of surface pressure at two locations with oblique angle to the main flow. Some non-uniform DMD modes indicate little decaying rate demonstrating more significant sustainability. These modes may also an indication to provoke the cross momentum transport nature, since the domain of similar harmonic motion was observed with an oblique angle.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 108 PROCEEDINGS OF THE FIFTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: J. Kruis, Y. Tsompanakis and B.H.V. Topping Paper 264 Proper Orthogonal Decomposition and Dynamic Mode Decomposition of Flow near the Leading Edge of a Two-Dimensional Flat Rectangular Prism H. Shirato¹, Y. Kawata², Y. Taniguchi¹ and I. Tsukamae¹ ¹Deapartment of Civil and Earth Resources Engineering, Kyoto University, Japan ²Obayashi Corporation, Tokyo, Japan doi:10.4203/ccp.108.264 purchase the full-text of this paper Full Bibliographic Reference for this paper H. Shirato, Y. Kawata, Y. Taniguchi, I. Tsukamae, "Proper Orthogonal Decomposition and Dynamic Mode Decomposition of Flow near the Leading Edge of a Two-Dimensional Flat Rectangular Prism", in J. Kruis, Y. Tsompanakis, B.H.V. Topping, (Editors), "Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 264, 2015. doi:10.4203/ccp.108.264 Keywords: proper orthogonal decomposition, dynamic mode decomposition, velocity field, surface pressure, span-wise correlation, aerodynamic force, bluff body, particle image velocimetry. Summary In this study, surface pressure and velocity field near the leading edge of a flat rectangular prism with a chord/depth ratio of 8.0 are measured in order to discuss the mechanism of correlation increase of flow near the prism and resulting surface pressure along a span-wise direction. The flow field is visualized then converted to a velocity vector field using a particle image velocimetry (PIV) technique, and the velocity vector space is decomposed using two different methods, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). The prism is set in still conditions in the turbulence grid of the wind tunnel. A two dimensional flow field in a plane (xy and xz planes, x: chord-wise, y: span-wise, z: vertical (normal to side surface) directions) is visualized using laser sheet and smoke generator. Surface pressure correlation between at the reference point near the leading edge and at the other point demonstrates a more correlated tendency if these two points are located along a line which has skew angle to the main flow direction. As for the mode decomposition of velocity field near the leading edge, some POD modes indicate non-uniform shape along span-wise direction. Particularly in some of the non-uniform modes for u and v in xy plane, there is a ridge in its mode shape with a skew angle to the main flow direction. This implies the cross momentum transport, which means the transport of u-momentum towards the span-wise direction by the v-component and of the v-momentum towards a chord-wise direction by the u-component, respectively. This may create higher correlation of surface pressure at two locations with oblique angle to the main flow. Some non-uniform DMD modes indicate little decaying rate demonstrating more significant sustainability. These modes may also an indication to provoke the cross momentum transport nature, since the domain of similar harmonic motion was observed with an oblique angle. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £75 +P&P)
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