Dynamic aerofracture of dense granular packings

Michael Niebling (1) , Renaud Toussaint (1, 2) , Eirik Grude Flekkøy (2, 3) , Knut Jørgen Måløy (2, 3)

1 IPGS-GE - Géophysique expérimentale (IPGS)
2 Department of Physics [Oslo]
3 Centre for Advanced Study at the Norwegian Academy of Science and Letters

A transition in hydraulically induced granular displacement patterns is studied by means of discrete numerical molecular dynamics simulations. During this transition the patterns change from fractures and fingers to finely dispersed bubbles. The dynamics of the displacement patterns are studied in a rectangular Hele-Shaw cell filled with a dense but permeable two-dimensional granular layer. At one side of the cell the pressure of the compressible interstitial gas is increased. At the opposite side from the inlet of the cell a semipermeable boundary is located. This boundary is only permeable towards the gas phase while preventing grains from leaving the cell. The imposed pressure gradient compacts the grains. In the process we can identify and describe a mechanism that controls the transition of the emerging displacement patterns from fractures and fingers to finely dispersed bubbles as a function of the interstitial gas's properties and the characteristics of the granular phase.

Mots clés: aerofracture; hydrofracture; fracture; pattern formation; morphogenesis; fluid injection; porous medium; rock

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]; Science des matériaux [cond-mat.mtrl-sci]

Michael Niebling, Renaud Toussaint, Eirik Grude Flekkøy, Knut Jørgen Måløy. Dynamic aerofracture of dense granular packings. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2012, 86, pp.061315. ⟨10.1103/PhysRevE.86.061315⟩. ⟨hal-00785096⟩