Intruder in a two-dimensional granular system: Effects of dynamic and static basal friction on stick-slip and clogging dynamics

Abstract

We discuss the results of simulations of an intruder pulled through a two-dimensional granular system by a spring, using a model designed to lend insight into the experimental findings described by Kozlowski et al. [Phys. Rev. E 100, 032905 (2019)]. In that previous study the presence of basal friction between the grains and the base was observed to change the intruder dynamics from clogging to stick-slip. Here we first show that our simulation results are in excellent agreement with the experimental data for a variety of experimentally accessible friction coefficients governing interactions of particles with each other and with boundaries. Then, we use simulations to explore a broader range of parameter space, focusing on the friction between the particles and the base. We consider a range of both static and dynamic basal friction coefficients, which are difficult to vary smoothly in experiments. The simulations show that dynamic friction strongly affects the stick-slip behaviour when the coefficient is decreased below 0.1, while static friction plays only a marginal role in the intruder dynamics.

Particle dynamics in two-dimensional point-loaded granular media composed of circular or pentagonal grains

“…Although these are significantly different packing fractions, the intruder exhibits qualitatively similar stick-slip dynamics, characterized by sequences of sticking periods in which the intruder is nominally stationary and slip events in which the intruder slips through the medium, for the two different particle shapes. (For disks, however, a packing fraction near φ = 0.65 yields intermittent flow, in which the intruder moves through the system with only occasional clogging events [2,3]. )…”

“…The response of a granular medium to loading from a single grain highlights fundamental connections across scales from grain-scale dynamics and forces to the macroscopic bulk response of the medium [1]. Simulations and experiments have characterized the dynamics of local intruding rods or grains as a function of parameters including basal friction [2,3], packing fraction [2][3][4], drive speed [4,5], drive force [6,7], and driving spring constant for studies of stick-slip dynamics [1][2][3]8]. However, in these works and many studies of granular materials in general, the model granular medium is composed of disks or spheres, idealized shapes rarely found in natural granular materials.…”

Self-assembly of self-propelled magnetic grains

“…We used Box2D for the DEM simulations [13], which has been successfully used to study granular flow [14], clogging [15], force networks [16], tapping [17], granular dampers [18], stick-slip [19], and soil mechanics [20]. This software library uses a constraint solver to handle contact and collision dynamics of rigid bodies.…”

On intermittency in sheared granular systems

“…Experimentally, the interactions between the particles have been extensively analyzed by using methods based on photoelasticity [5,[11][12][13][14][15][16]. The same information can be obtained for a wide variety of systems [17][18][19][20][21][22] by rela-tively straightforward simulations based on discrete element methods. Therefore, a significant amount of research has been carried out and here we mention only a few examples.…”