Full-field pressure from snapshot and time-resolved volumetric PIV

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Abstract

This paper deals with pressure estimation from snapshot and time-resolved three-component (3C) volumetric PIV data using Taylor’s hypothesis, an Eulerian and a pseudo-Lagrangian approach. The Taylor’s hypothesis approach has been shown to provide accurate results for pressure in the case of 3C planar PIV data with an appropriate choice of convection velocity (de Kat and Ganapathisubramani 2013), and here we extend its use on 3C volumetric velocity snapshots. Application of the techniques to synthetic data shows that the Taylor’s hypothesis approach performs best using the streamwise mean as the convection velocity and is affected the least by noise, while the Eulerian approach suffers the most. In terms of resolution, the pseudo-Lagrangian approach is the most sensitive. Its accuracy can be improved by increasing the frame time-separation when computing the material derivative, at the expense of volume loss from fluid parcels leaving the FOV. Comparison of the techniques on turbulent boundary layer data with DNS supports these observations and shows that the Taylor’s hypothesis approach is the only way we can get pressure when time information is not present.