Plenary Lecture
PIV Measurement of Flow around an Arbitrarily Moving Body
Professor Hyung Jin Sung
Department of Mechanical Engineering
KAIST
Korea
E-mail: hjsung@kaist.ac.kr
Abstract: This paper presents a PIV (particle image velocimetry) image processing method for measuring flow velocities around an arbitrarily moving body. This image processing technique uses a contour-texture analysis based on user-defined textons to determine the arbitrarily moving interface in the particle images. After the interface tracking procedure is performed, the particle images near the interface are transformed into Cartesian coordinates that are related to the distance from the interface. This transformed image always has a straight interface, so the interrogation windows can easily be arranged at certain distances from the interface. Accurate measurements near the interface can then be achieved by applying the window deformation algorithm in concert with PIV/IG (interface gradiometry). Quantitative evaluations of this method were performed by applying it to computer-generated images and actual PIV measurements. A three-dimensional (3D) particle image velocimetry (PIV) measurement technique capable of simultaneously monitoring 3D fluid flows and the structure of an arbitrarily moving surface embedded in the flow is proposed. An optimal exposure time for surface and particle imaging was identified using red fluorescent tracer particles in conjunction with a long-pass glass filter. The particle image and surface image were then separated using an image separation process that relied on the feature scaling differences between the particles and the surface texture. A feature detection process and a matching process facilitated estimation of the 3D surface points, and the 3D surface structure was modeled by Delaunay triangulation. The particle volume reconstruction algorithm constrained the voxels inside the surface structure to zero values to minimize ghost particle generation. Volume self-calibration was employed to improve the reconstruction quality and the triangulation accuracy. Three-dimensional experiments that modeled the flows around an eccentric rotating cylinder and a flapping flag were conducted to validate the present technique.
Brief Biography of the Speaker: Hyung Jin Sung received his Ph.D. degree in Mechanical Engineering in 1984 from KAIST (Korea Advanced Institute of Science & Technology), Korea. He is a professor in the department of Mechanical Engineering, KAIST. His current research interests include turbulence, flow control, measurement, flow-structure interaction, micro/bio fluidics, and fuel cell. More recent contributions have explored the liquid transfer on printed electronics. Since 1986 he has served as visiting professor in UIUC, Hokkaido University, and UCLA for several years. Prof. Sung has served on a chief of fluid engineering of KSME (Korean Society of Mechanical Engineers). He conducted a research in collaboration with Cavendish laboratory of Cambridge University and developed micro devices for fluid mixing and pumping. Since 1997 he has received academic awards from KSME and KAIST. Moreover, in 2003 he won a commendation from the President of Korea in appreciation of his research. He is author of about 190 papers published in international journals.