Time-Accurate Measurement of Pressure From Particle Image Velocimetry Data (Keynote)

This paper explores the challenges associated with the determination of pressure from DPIV-measured planar velocity fields for time-dependent incompressible flows. Several methods that have been previously explored in the literature are compared, including direct integration of the pressure gradients, and solution of different forms of the pressure Poisson equations. Their dependence on grid resolution, sampling rate, and velocity measurement error levels was quantified using artificial data of two ideal sample flow fields — a decaying vortex flow and pulsatile flow between two parallel plates. The need for special attention to mitigate the velocity error propagation in the pressure estimation is also addressed using a physics-preserving method based on Proper Orthogonal Decomposition. Finally, the methods developed are applied to sample Time Resolved DPIV experimental data corresponding to separated flow over an airfoil and pulsatile flow through an artery. The results demonstrate that there is no unique or optimum method for estimating the pressure field and the resulting error will depend highly on the type of the flow. Estimated errors can vary from less than 1% to over 100% with respect to the expected value. However, the analysis offers valuable insight that allows optimizing the choice of methods and parameters based on the flow under consideration.