Design & Implementation of a 3D-PTV System

Abstract: The dream of experimental fluid dynamicists is to be able to measure complex, three-dimensional turbulent flow fields globally with very high spatial and temporal resolution. While we are still far from fully realizing this dream, significant progress has been made towards this goal during the last three decades. Early quantitative measurement methods using Pitot tubes, Venturi tubes and later measurement methods, such as Hot Wire Anemometry (HWA) and Laser-Doppler Anemometry (LDA), by their nature, were measurement methods that provided instantaneous velocity signals at single-points through time. Early emphasis in turbulence research and its theoretical advancement therefore necessitated a statistical description of turbulent flow fields, which relied heavily upon measurements provided by these single-point measurement techniques. Since the early seventies, the discovery of the existence of three-dimensional coherent structures within turbulent flows using qualitative flow visualization methods (i.e. shadowgraphs, Schlieren systems, dye injection, etc) has been of significant interest for turbulence researchers. While flow visualization techniques have been around since the days of Prandtl, it is only due to the advent of modern imaging, laser, and data acquisition technology has allowed for qualitative flow visualization to become quantitative. These advents have allowed for the development and advancement of are relatively new measurement technique, Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) in two dimensions, and more recently in 3 dimensions. Because of its ability to provide global two/three-dimensional kinematic information as well as its ability to map the evolution of coherent structures through time, PIV/PTV has become a powerful tool in studying, understanding, and modeling fluid flow behavior. In this talk, I will describe the particulars of the 3D Particle Tracking Velocimetry method we have developed and touch on some applications in microflows and LES studies.