LOW-COST, HIGH-RESOLUTION DPIV FOR MEASUREMENT OF TURBULENT FLUID-FLOW

An optimized cross-correlation based Imaging Velocimetry system is des cribed and its performance is evaluated in numerical and physical expe riments. Given a discrete image array pair, the flow seeding and image processing parameters are optimized to maximize displacement accuracy , regardless of the computational cost; collectively these techniques are known as Correlation Imaging Velocimetry (CIV). Order of magnitude improvements over standard DPIV methods can readily be obtained, allo wing high resolution measurements to be made with low cost standard re solution cameras. Fundamental limits on the measurable range of length , velocity and vorticity scales are identified, and related to those e ncountered in homogeneous, 3D turbulence. The current restrictions app ly to all imaging velocimetry measurements; some paths for future rese arch that are likely to be profitable are identified, together with so me that are not. Extensive use of CIV in this and other laboratories h as allowed direct verification of these optimization principals.