A correction method for measuring turbulence kinetic energy dissipation rate by PIV

The accuracy of turbulent kinetic energy (TKE) dissipation rate measured by PIV is studied. The critical issue for PIV-based dissipation measurements is the strong dependency on the spatial resolution, Delta x, as reported by Saarenrinne and Piirto (Exp Fluids Suppl:S300-S307, 2000). When the PIV spacing is larger than the Kolmogorov scale, eta, the dissipation is underestimated because the small scale fluctuations are filtered. For the case of Delta x smaller than the Kolmogorov scale, the error rapidly increases due to noise. We introduce a correction method to eliminate the dominant error for the small Delta x case. The correction method is validated by using a novel PIV benchmark, random Oseen vortices synthetic image test (ROST), in which quasi-turbulence is generated by randomly superposing multiple Oseen vortices. The error of the measured dissipation can be more than 1,000% of the analytical dissipation for the small Delta x case, while the dissipation rate is underestimated for the large Delta x case. Though the correction method does not correct the underestimate due to the low resolution, the dissipation was accurately obtained within a few percent of the true value by using the correction method for the optimal resolution of eta/10 < Delta x < eta/2.