@misc{indiciaeca2f8028eecf,
  title = {Density waves in dry granular media falling through a vertical pipe.},
  author = {T Raafat and JP Hulin and HJ Herrmann},
  year = {1996},
  doi = {10.1103/physreve.53.4345},
  url = {https://pubmed.ncbi.nlm.nih.gov/9964767/},
  note = {Source identifier: 9964767}
}