Characteristics of large three-dimensional heaps of particles produced by ballistic deposition from extended sources

Abstract

This paper reports a detailed numerical investigation of the geometrical and structural properties of three-dimensional heaps of particles. Our goal is the characterization of very large heaps produced by ballistic deposition from extended circular dropping areas. First, we provide an in-depth study of the formation of monodisperse heaps of particles. We find very large heaps to contain three new geometrical characteristics: they may display two external angles of repose, one internal angle of repose, and four distinct packing fraction (density) regions. Such features are found to be directly connected with the size of the dropping zone. We derive a differential equation describing the boundary of an unexpected triangular packing fraction zone formed under the dropping area. We investigate the impact that noise during the deposition has on the final heap structure. In addition, we perform two complementary experiments designed to test the robustness of the novel features found. The first experiment considers changes due to polydispersity. The second checks what happens when letting the extended dropping zone to become a point-like source of particles, the more common type of source.

The microscopic structure of mono-disperse granular heaps and sediments of particles on inclined surfaces

“…For a full discussion of the properties of the model see ref. 30. Insofar, the results presented here may be specific for this type of dynamics and their possible generalization was not investigated.…”

Structure of a three-dimensional nano-powder subjected to repeated fragmentation and sedimentation

“…When a particle reaches a stable position either on three previously dropped spheres or on the ground, it is considered fixed and cannot move anymore. This particle dynamics has been used to study a variety of systems and their phenomena, such as packing properties of sediments [3,5,6], their surface properties [7], segregation by size [8,9], filtration [10], convective heap formation [11], structure evolution in rotating drums [12][13][14], and how the structure in a heap and its angle of repose are related to the deposition process [15,16]. In section 2.1 we present a non-trivial generalization of the Visscher-Bolsterli model to agglomerates in three dimensions.…”

Systematic Onset of Periodic Patterns in Random Disk Packings

“…In the last few years, we considered different aspects of packing problems. For instance, we found that very large three-dimensional heaps of particles display novel geometric characteristics involving internal and external angles of repose as well as distinct densities within the packing [17,18]. We also studied the structural defects present in large disks packings, showing the existence of a nonzero residual density of defects that obeys a power-law distribution as a function of the channel width [19].…”

“…Additional examples are discussed in the Supplemental Material [20]. Disks piles were generated using the well-known ballistic deposition algorithm [15,[17][18][19][21][22][23][24][25]. The implementation of this algorithm was described in detail elsewhere, in our previous study of the residual defect density in disk deposits [19].…”