title: Drag on intruders in granular beds: a boundary layer approach.
abstract: We performed a parametric study of the drag on vertical intruders with uniform cross sections of different sizes and shapes, from which we developed a semiempirical model. Baffling techniques were used to isolate the contributions of the intruder's different subsurfaces, and we observed size effects and force focusing on edges. We propose a boundary layer approach, whereby the drag is the surface integral of an effective stress over a monolayer of particles contacting the intruder. The stress has a simple lithostatic dependence and is a function of the orientation relative to the intruder's direction of motion. This approach is experimentally verified and is consistent with the semiempirical model.
authors.affiliation: Department of Physics, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Goldsmith
authors.forename: Hong
authors.initials: H
authors.lastname: Guo
authors.forename: Shelby N
authors.initials: SN
authors.lastname: Hunt
authors.forename: Mingjiang
authors.initials: M
authors.lastname: Tao
authors.forename: Stephan
authors.initials: S
authors.lastname: Koehler