Development of Optical Three Dimensional Measurement Techniques for Fluid Dynamics

Available from UMI in association with The British Library. This thesis presents two new optical methods which enable the simultaneous measurement of the three components of fluid velocity over an extended volume of a flow. The first, termed stereo particle image velocimetry, was an adaptation of the conventional particle image velocimetry (PIV) method. The second combined in-line holographic methods used with a stereo viewing technique. This method, named stereo in-line holography, enabled the location of seed particle positions along the recording optical axis to be more accurately defined. The image processing algorithms used in this procedure were also found to be extremely efficient. Special emphasis is placed on stereo camera modeling and the recovery of 3-D information from 2-D perspective images. Stereo image processing techniques are discussed which enable the matching of the two stereo images to be made more precisely. The stereo measurement facility developed for PIV was also adapted to provide information about the surface profile of freely propagating gravity water waves. Results and conclusions are presented based on the application of each technique to a variety of flows (air and water). The stereo PIV method was suited for use in the measurement over a wide velocity range, whereas the holographic method as described could be used only to investigate low speed flows. Both methods require low seeding density.