Error propagation dynamics of PIVbased pressure field calculation (3): What is the minimum resolvable pressure in a reconstructed field?
Abstract
An analytical framework for the propagation of velocity errors into PIVbased pressure calculation is extended. Based on this framework, the optimal spatial resolution and the corresponding minimum fieldwide error level in the calculated pressure field are determined. This minimum error can be viewed as the smallest resolvable pressure. We find that the optimal spatial resolution is a function of the flow features (patterns and length scales), fundamental properties of the flow domain (e.g., geometry of the flow domain and the type of the boundary conditions), in addition to the error in the PIV experiments, and the choice of numerical methods. Making a general statement about pressure sensitivity is difficult. The minimum resolvable pressure depends on competing effects from the experimental error due to PIV and the truncation error from the numerical solver, which is affected by the formulation of the solver. This means that PIV experiments motivated by pressure measurements should be carefully designed so that the optimal resolution (or close to the optimal resolution) is used. Flows ($Re = 1.27 \times 10^4$ and $5\times 10^4$) with exact solutions are used as examples to validate the theoretical predictions of the optimal spatial resolutions and pressure sensitivity. The numerical experimental results agree well with the rigorous analytical predictions. We also propose an \textit{a posterior} method to estimate the contribution of truncation error using Richardson extrapolation and that of PIV error by adding artificially overwhelming noise. We also provide an introductory analysis of the effects of interrogation window overlap in PIV in the context of the pressure calculation.
 Publication:

arXiv eprints
 Pub Date:
 July 2018
 arXiv:
 arXiv:1807.03958
 Bibcode:
 2018arXiv180703958N
 Keywords:

 Physics  Fluid Dynamics
 EPrint:
 This is a significant extension of the previous version. Correspondence and requests should be addressed to Zhao Pan (email: zhao.pan@uwaterloo.ca)