Experiences of turbulence measurement with PIV*

Abstract

The application of particle image velocimetry to turbulence measurement is described. An analysis of physically necessary spatial resolution is presented by using a model spectrum function. A comparison is made with hot-wire anemometry. Some aspects of spatial filtering and two-dimensional sampling are presented with a comparison to large-eddy simulation. The estimation of time mean turbulence quantities from the measured vector fields in a laboratory mixer is used as an example. The measurement results for two different image sizes at the same position in the flow field are compared with different interrogation area sizes. The assumed dependence of the velocity field on the interrogation area size could not be confirmed. The image size seems to produce dependence in all estimated quantities. The measurement errors are critical for the achieved results.

PIV study of the flow field generated by a sawtooth impeller

“…Saarenrinne et al (2001) ) was estimated to be around 36 μm. It follows that the PIV resolution of 28 (at the 1 mm filtering scale) is insufficient to determine the dissipation rate directly from its fundamental definition.…”

Particle image velocimetry measurement of indoor airflow field: A review of the technologies and applications

“…It is noticeable that velocity measurements are not free from errors, especially for the low-velocity measurements in room environment [94]. Unlike other anemometers, PIV is a measuring technique whose accuracy is directly determined by both the displacement error and the uncertainty in the time delay between pulses.…”

“…Then the image acquisition and evaluation procedure produces its own errors. The accuracy of calculated velocity data mainly depend on the quality of particle image, size of interrogation area and the statistical correlation method [30,[94][95][96]. Moreover, the expertises of the researcher also influence the measurement accuracy.…”

A Multi‐Block Approach to Obtain Angle‐Resolved PIV Measurements of the Mean Flow and Turbulence Fields in a Stirred Vessel

“…Previous experimental studies using PIV, for example by Baldi et al [4] and by Saarenrinne et al [5,6] have shown that it should also be possible to calculate dissipation rates directly from instantaneous velocity gradients in the flow using Eq. (2).…”

“…Saarenrinne [5] estimates that a resolution of about 2 k K is required to reach about 90 % of the dissipation rate, or about 9 k K to reach 65 % of e. In contrast, the turbulence kinetic energy, k, requires much less resolution, since the majority of k resides in the larger eddies. However, a separate requirement may be to visualize coherent structures in the flow, or to obtain integral length scales and thus it may be necessary to measure also across larger fields of view.…”