Physics Today, Backscatter, March 2018
Cracking the particle packing
Tilted frictional fingers
Eriksen J.A., Toussaint R., Måløy K.J., Flekkøy E.G., Galland O. and Sandnes B. Pattern formation of frictional fingers in a gravitational potential. Phys. Rev. Fluids 3, 013801 (2018). Eriksen_PRFluids2018_preprint
Frictional fingers in gravity
Pattern formation of frictional fingers in a gravitational potential
Jon Alm Eriksen, Renaud Toussaint, Knut Jørgen Måløy, Eirik Flekkøy, Olivier Galland, and Bjørnar Sandnes
Phys. Rev. Fluids 3, 013801 – Published 3 January 2018
Gravity induces parallel growth of finger structures which forms when air displaces a granular-liquid mixture. The alignment direction, which varies between horizontal and vertical, is explained by the interplay between surface tension, yield stresses, and the hydrostatic potential.
Gas-driven fracturing
Gas-Driven Fracturing of Saturated Granular Media
James M. Campbell, Deren Ozturk, and Bjørnar Sandnes
Phys. Rev. Applied 8, 064029 – Published 29 December 2017
Gas-driven fracturing underlies both natural and industrial processes, such as volcanic degassing, methane venting, stimulated hydrocarbon extraction, and treatment of contaminated soil. The authors show how in such a complex system the capillary, frictional, and viscous interactions together produce a range of fracture patterns, with cracks separated by a characteristic length that varies based on the conditions. Discovering how material properties and injection rate affect these patterns helps to establish a physics framework for optimizing permeability and assessing risk in gas-driven fracturing of hydrocarbon reservoirs and remediation of polluted soil.
