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Magnetic Janssen effect.

L Thorens1,2, K J Måløy2, M Bourgoin1

  • 1Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS, Laboratoire de Physique, Lyon, France.

Nature Communications
|May 1, 2021
PubMed
Summary
This summary is machine-generated.

Researchers control granular materials using magnetic fields, demonstrating a magnetic Janssen effect. This allows fine-tuning the apparent mass of granular columns, enabling new functional jammed materials.

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Area of Science:

  • Soft Matter Physics
  • Granular Materials Science
  • Applied Magnetism

Background:

  • The Janssen effect describes pressure saturation in granular materials within silos due to grain-grain and grain-wall friction.
  • Traditional understanding relies on static frictional interactions, limiting control over granular column properties.
  • Controlling granular behavior in confined spaces is crucial for various engineering applications.

Purpose of the Study:

  • To investigate the influence of magnetic fields on the frictional interactions within granular materials.
  • To demonstrate a novel method for controlling the apparent mass of granular columns.
  • To explore the potential for designing tunable jammed materials using magnetic fields.

Main Methods:

  • Utilized ferromagnetic grains to enable magnetic manipulation of inter-grain interactions.
  • Applied an external magnetic field to influence pairwise interactions between magnetized grains.
  • Measured the resulting radial forces and changes in the apparent mass of the granular column.

Main Results:

  • Demonstrated that an external magnetic field induces anisotropic pairwise interactions in ferromagnetic grains.
  • Observed a tunable radial force along the container walls, controlled by the magnetic field's amplitude and direction.
  • Showcased the ability to fine-tune the apparent mass of the granular column via the magnetic Janssen effect.

Conclusions:

  • The magnetic Janssen effect offers a new mechanism for actively controlling granular material properties.
  • This approach allows for precise tuning of static and dynamic properties of granular systems in confined geometries.
  • Findings open avenues for developing advanced functional jammed materials with tunable characteristics.