Proper Orthogonal Decomposition of Round Jet Turbulence Measured by Dynamic PIV

In this study, we have used Dynamic PIV to measure the time-resolved turbulent velocity distributions of the near field flow of round jet turbulence. The Dynamic PIV system allows capturing particle images with kilohertz frame rate, mega-pixel resolution and gigabyte memory. We apply the system to study the spatial and temporal evolution of the coherent vortical structures in the near field of the round jet. 2-D and 3-D Proper Orthogonal Decomposition (POD) are employed to extract the coherent structures. The 3-D POD shows advantages over 2-D POD. The spatial distribution and temporal evolution of the flow structures extracted by 3-D POD are uncovered.