title: Granular fingers on jammed systems: new fluidlike patterns arising in grain-grain invasion experiments.
abstract: In this Letter we report spontaneous pattern formation in dense granular assemblies confined to a Hele-Shaw cell and quasistatic regime. Varied unexpected patterns, ranging from rounded to fingered, are observed due to the displacement of one granular material by another. Computer simulations reproduce the major features observed in these experiments. Two mechanisms are responsible for the pattern formation: crystallization of the injected grains and plastic deformation of the displaced grains. The experiment suggests analogies with viscous fingering and jamming transition experiments.
authors.affiliation: Departamento de Física, Universidade Federal de Viçosa, 36570-000, Viçosa, MG, Brazil.
authors.forename: S F
authors.initials: SF
authors.lastname: Pinto
authors.forename: M S
authors.initials: MS
authors.lastname: Couto
authors.forename: A P F
authors.initials: AP
authors.lastname: Atman
authors.forename: S G
authors.initials: SG
authors.lastname: Alves
authors.forename: A T
authors.initials: AT
authors.lastname: Bernardes
authors.forename: H F V
authors.initials: HF
authors.lastname: de Resende
authors.forename: E C
authors.initials: EC
authors.lastname: Souza
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D003198:Computer Simulation; D019344:Lactic Acid / Q000737:chemistry*; D008962:Models, Theoretical; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D013232:Steel / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D011108:Polymers; D011137:Polystyrenes; D013232:Steel; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D002244:Carbon