Application potential of advanced PIV algorithms for industrial applications

Abstract

Parallel to the increased use of particle image velocimetry in applied research and development, the need for robust processing algorithms capable of reliably tackling an ever increasing spectrum of applications arises. The investigated flows are frequently dominated by high shear rates and/or strong vortices with a high spatial and temporal variation. Traditional PIV processing algorithms relying on a spot-by-spot analysis of the images frequently fall short of recovering the flow field at the spatial resolution offered by the original PIV recording. More advanced algorithms – frequently also referred to as second-order accurate methods – rely on a pyramid-based grid refinement strategy to increase spatial resolution. At the same time iterative deformation schemes are applied to the images to increase the matching efficiency of the correlation-based PIV technique. Whilst the deformation schemes can be applied locally using an interrogation spot at time, the technique of global image deformation based on displacement estimates of prior interrogation passes has proven to be both efficient and highly reliable for a wide range of applications. The presentation will give an overview of a PIV algorithm utilizing these advanced concepts that has been in use at DLR over the past year. Its performance gain in comparison to traditional algorithms will be illustrated using several examples of recent PIV measurements. Estimates concerning the algorithm’s increased processing-cost, its convergence and stability, as well as a few important implementation specific issues are also given.