Inquiry regarding anomalous PIV velocity vectors in granular flow analysis
Bastián Araya Jofré
Dear Dr. William,
I hope you are doing well.
I would like to inform you that I am currently working on a project involving the analysis of a granular flow intended to represent an avalanche in an inclined channel. For this purpose, a high-speed camera is used to capture the flow from a top (overhead) view, oriented perpendicularly to the channel bed.
When analyzing this flow using PIVlab, the resulting velocity field has raised some concerns, as the computed vectors exhibit anomalous behavior in certain cases. First, while the flow has not yet entered the field of view, the software generates vectors in random directions (as shown in Figure 1, highlighted in red), which could be interpreted as noise. Additionally, once the flow is present and undergoing deposition, some vectors appear to point in directions opposite to those expected based on the flow motion (as shown in the red-highlighted regions in Figure 2).
Based on these observations, I am wondering whether these erroneous vectors could be associated with an excessively high vector field resolution, calibration issues, or the lighting conditions of the experimental setup. In particular, there is an LED light source above the channel that appears to flicker during recording, which may be affecting the analysis.
Could you please provide guidance or suggest possible corrections to address this issue?
Thank you in advance for your time and consideration.
Kind regards,
Bastian Araya
