A novel 4D digital holographic PIV/PTV (4D-DHPIV/PTV) methodology using iterative predictive inverse reconstruction

Digital imaging array technology and processing power are continuously improving and have reached a state where 4-dimensional (i.e. time-resolved 3C-3D) digital holographic PIV/PTV (4D-DHPIV/PTV) methods can be considered for macro fluid mechanics and turbulence investigations. This paper presents an in-line 4D-DHPIV/PTV methodology, which in addition to including the standard digital hologram reconstruction, incorporates advanced digital filtering to remove the virtual image effect, 3-dimensional volume deconvolution to reduce the depth-of-focus problem and the virtual image, followed by an efficient one-pass 3-dimensional clustering algorithm coupled with a predictive inverse reconstruction approach to increase the particle reconstruction dynamic range and 3-dimensional reconstruction domain, which is accelerated using particle position prediction. In addition to the presentation of the details of this novel 4D-DHPIV/PTV method, performance results pertaining to bias particle position error and the uncertainty associated with the particle position are presented as a function of (i) particle concentration and (ii) the shot noise present in the digitally recorded hologram. An experiment to measure laminar micro-channel flow has been performed to demonstrate the 4D-DHPIV/PTV methodology.