Dynamic X-ray radiography reveals particle size and shape orientation fields during granular flow

Area of Science:

• Physics
• Materials Science
• Engineering

Background:

• Granular materials exhibit particle segregation by size and alignment by shape during flow.
• Understanding the impact of these fabric changes on bulk flow remains a challenge.
• Novel non-invasive techniques are needed to observe internal granular material dynamics.

Purpose of the Study:

• To introduce a new experimental technique using dynamic X-ray radiography for observing internal granular material flow.
• To measure spatiotemporal distributions of particle size and shape orientation.
• To complement these measurements with velocity field data.

Main Methods:

• Dynamic X-ray radiography was employed as the primary non-invasive technique.
• Fourier transformation was used to extract particle size and shape orientation distributions.
• Image correlation was utilized for complementary velocity field measurements.

Main Results:

• X-ray radiography successfully captured bulk flow properties, unlike optical methods limited to boundary layers.
• The study revealed dynamic particle alignment with streamlines during silo discharge.
• Observed phenomena are critical for preventing granular flow instabilities and clogging.

Conclusions:

• Dynamic X-ray radiography is a powerful tool for studying granular material flow.
• The technique provides insights into particle fabric evolution and its effect on bulk flow.
• Findings are applicable to various soft matter systems, including foams and biological materials.