Errors in particle tracking velocimetry with high-speed cameras

TL;DR

This paper investigates how high-speed cameras affect velocity measurement errors in particle tracking velocimetry, revealing that errors depend on frame rate and sampling interval, impacting derived quantities like kinetic temperature.

Contribution

It identifies the sources of velocity errors in high-speed PTV and demonstrates methods to mitigate these errors, highlighting their effect on physical measurements.

Findings

Velocity errors increase with higher frame rates due to particle-position uncertainty.

Kinetic temperature measurements depend on sampling time interval, not just particle velocities.

Artifacts in autocorrelation functions become more pronounced with smaller sampling intervals.

Abstract

Velocity errors in particle tracking velocimetry (PTV) are studied. When using high-speed video cameras, the velocity error may increase at a high camera frame rate. This increase in velocity error is due to particle-position uncertainty, which is one of two sources of velocity errors studied here. The other source of error is particle acceleration, which has the opposite trend of diminishing at higher frame rates. Both kinds of errors can propagate into quantities calculated from velocity, such as the kinetic temperature of particles or correlation functions. As demonstrated in a dusty plasma experiment, the kinetic temperature of particles has no unique value when measured using PTV, but depends on the sampling time interval or frame rate. It is also shown that an artifact appears in an autocorrelation function computed from particle positions and velocities, and it becomes more severe when a small sampling-time interval is used. Schemes to reduce these errors are demonstrated.