Fluid Flow Visualization by Three-dimensionally Reconstructed Tracer Path Lines

Article type: Research Article

Authors: Machacek, M. | Rösgen, T.

Affiliations: Institute of Fluid Dynamics, ETH Zürich, Sonneggstr. 3, CH-8092 Zürich, Switzerland. E-mail: machacek@ifd.mavt.ethz.ch | Institute of Fluid Dynamics, ETH Zürich

Abstract: The development of a measurement system for the visualization, topological classification and quantitative analysis of complex flows in large-scale wind tunnel experiments is described. A new approach is sought whereby the topological features of the flow, e.g. stream lines, separation and reattachment regions, stagnation points and vortex lines are extracted directly and are preferably visualized in real-time in a virtual wind tunnel environment. The system is based on a stereo arrangement of two CCD cameras. A frame rate of 120 f/s allows measurements at high flow velocities. Helium filled soap bubbles are used as tracer particles. The present paper describes a simple camera calibration procedure for large measurement environments and examines the problem of fast and accurate reconstruction of path lines in three dimensions, which will enable true three-dimensional and time-resolved fluid flow visualization. Experimentally obtained visualization results for a free-stream flow, flow around a circular plate and flow over a delta wing are presented.

Keywords: Three-dimensional flow visualization, Topology, Path lines, Camera calibration, Helium-filled bubbles

Journal: Journal of Visualization, vol. 6, no. 2, pp. 115-124, 2003