Size segregation of irregular granular materials captured by time-resolved 3D imaging
Parmesh Gajjar1, Chris G Johnson2, James Carr3
1Henry Moseley X-ray Imaging Facility, Department of Materials Science, The University of Manchester, Manchester, M13 9PL, UK. parmesh.gajjar@alumni.manchester.ac.uk.
Scientific Reports
|April 20, 2021
Summary
The Brazil nut effect, or size-segregation, is better understood using X-ray CT. Largest nuts rise only after rotating vertically, then flattening at the surface.
Area of Science:
- Physics
- Materials Science
- Engineering
Background:
- The Brazil nut effect describes how larger particles rise to the top in a mixture when shaken.
- Previous studies faced challenges in observing granular material dynamics.
- Understanding particle motion is crucial for industrial applications.
Purpose of the Study:
- To visualize and analyze the 3D motion of large particles during size-segregation.
- To investigate the role of particle shape and orientation in the Brazil nut effect.
- To provide insights for improved simulations and predictive models.
Main Methods:
- Utilized time-lapse X-ray Computed Tomography (CT) to observe particle dynamics.
- Studied a mixture of granular materials, focusing on the movement of larger 'Brazil nuts'.
- Analyzed particle rotation and orientation during the segregation process.
Main Results:
- Brazil nuts initiate upward movement only after rotating towards a vertical orientation.
- Particles flatten upon reaching the surface.
- Identified factors influencing why some Brazil nuts do not segregate.
Conclusions:
- Particle shape and orientation are critical factors in granular segregation.
- 3D tracking of particle motion enables more realistic simulations.
- Findings have implications for industries beyond food, including pharmaceuticals and mining.
