  Granular intrusion is commonly observed in natural and man-made settings.
Unlike single-phase media like solids and fluids, granular media can
simultaneously display fluid-like and solid-like characteristics in a variety
of intrusion scenarios. This trans-phase behavior increases the difficulty of
accurately modeling these and other yielding (or flowable) materials.
Micro-scale modeling methods, such as DEM (Discrete Element Method), capture
this multiphase behavior by modeling the media at the grain scale, but interest
often lies in the macro-scale characterizations of such systems. We examine the
efficacy of a macro-scale continuum approach in modeling and understanding the
physics and macroscopic phenomena behind a variety of granular intrusions cases
using two basic frictional yielding constitutive models. We compare predicted
granular force response and material flow to data in four 2D intrusion cases:
(1) depth-dependence forces responses in horizontal submerged-intruder motion;
(2) separation-dependent drag variation in parallel-plate vertical-intrusion;
(3) initial-density-dependent drag fluctuations in free surface plowing, and
(4) flow zone development in vertical plate intrusions in under-compacted
granular media. Our continuum modeling approach captures the flow process and
drag forces in each of these cases compared to experimental data while
providing key meso- and macro-scopic insights. Our study highlights how
continuum modeling approaches provide an alternative for efficient modeling as
well as conceptual understanding of various granular intrusion phenomena
