Physics of Granular Matter (SoSe 2025)

Prof. Dr. Matthias Sperl

Matthias dot Sperl at dlr.de

Dr. Jan Gabriel

Jan dot Gabriel at dlr.de

Dr. Peidong Yu

Peidong dot Yu at dlr.de

Dr. Till Kranz

kranz at thp.uni-koeln.de

News

Course Description

Granular matter is an example for a physical system far from equilibrium: Dissipative collisions among the constituent particles break time reversal symmetry and a constant energy input is necessary to establish a non-equilibrium steady state. The course shall give an overview of the current understanding of the physics of granular materials comprising theory, computer simulation as well as laboratory and microgravity experiments. Beyond the current state of the art, open research questions shall be reviewed as well as implications for applications.

Topics include

Granular Phenomena in Nature
Sand Piles; Avalanches; Formation and Migration of Dunes, etc.
Granular Packings
Mechanical Properties; Critical Behavior; Non-Destructive Techniques
Granular Fluids
Kinetic Theory; Rheology; Computer Simulation; Experiments in Microgravity

Lecture

The lecture takes place on Monday 14:00 – 15:30 in room 0.02 in the new Theory building

Recommended Reading

Seminar

The seminar takes place on Monday 16:00 – 16:45. The dates are according to individual agreement. Questions should be addressed to Matthias Sperl

Suggested Topics

Phenomena

  1. Radial segregation in rotating drum http://iopscience.iop.org/article/10.1209/0295-5075/30/1/002/meta
  2. Axial segregation in rotating drum https://link.springer.com/article/10.1007/s10035-003-0141-y; More axial segregation https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.105.118001
  3. Granular convection https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.100.078002
  4. Dune size distribution https://link.springer.com/article/10.1007/s10035-008-0120-4 ; Dunes on Mars https://journals.aps.org/pre/abstract/10.1103/PhysRevE.76.041307
  5. Stress dip under sandpile https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.98.028001
  6. Frustrated Bearings https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.125.104301

Experiments

  1. Brazil nut effect https://journals.aps.org/pre/abstract/10.1103/PhysRevE.74.011307
  2. Wet granular matter https://www.nature.com/articles/nmat2117
  3. Granular Glass Transition https://journals.aps.org/pre/abstract/10.1103/PhysRevE.74.031308
  4. Beads in μg https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.208007; Rods in μg https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.214301
  5. Measuring coefficient of restitution https://aip.scitation.org/doi/abs/10.1063/1.868282
  6. Force chains https://www.nature.com/articles/nature03805
  7. Cratering https://www.nature.com/articles/nphys583

Experimental Techniques

A variety of imaging and tracking techniques could be discussed

Simulation

  1. Cundall-Strack http://websrv.cs.umt.edu/classes/cs477/images/0/0e/Cundall_Strack.pdf
  2. Event Driven https://www.sciencedirect.com/science/article/pii/0021999191902227
  3. Fluidized bed https://www.sciencedirect.com/science/article/pii/S003259100700592X
  4. Jamming https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.88.075507

Theory

  1. Dune Model https://journals.aps.org/pre/abstract/10.1103/PhysRevE.66.031302
  2. Tails of the velocity distribution https://journals.aps.org/pre/abstract/10.1103/PhysRevE.65.040301
  3. Force tiles https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.100.238001
  4. Instability of homogeneous granular gas https://aip.scitation.org/doi/abs/10.1063/1.858716
  5. Coefficient of restitution for viscoelastic particles https://journals.aps.org/pre/abstract/10.1103/PhysRevE.78.051304
  6. Modified Fouriers law https://pubs.acs.org/doi/abs/10.1021/jp0736490
  7. Inelastic collapse https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.81.1142