Effect of friction on the angle of repose of elongated particles
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Bibliographic record
Abstract
The angle of repose ( A O R ) is a key parameter in powder engineering, primarily influenced by the pouring process, the inter-particle constitutive laws and particle shape. Therefore, the A O R of a bulk material is intuitively linked to its macromechanical internal friction angle. Previous studies indicate that more irregular particle shapes, such as angular or elongated particles, increase both shear strength and A O R . However, in granular materials with highly irregular shapes and low interparticle friction (or frictionless conditions), this trend reverses for the shear resistance. Despite these results, studies on the A O R of such materials are rare and the physical mechanisms of this behavior are unclear. This study investigates the A O R of dry, cohesionless granular piles composed of elongated particles using 3D DEM simulations. To represent a wide range of conditions specific to various industrial processes — including pharmaceuticals, food engineering, geotechnics, and mining — we extensively vary particle characteristics, focusing on particle elongation and interparticle friction. The particles, modeled as rounded-cap cylinders, have aspect ratios (length/diameter) ranging from 1 (spheres) to 4. For high interparticle friction ( μ > 0 . 2 ), the A O R increases systematically with elongation. However, at low friction, a critical aspect ratio of 1.5 emerges, beyond which the tendency changes and the A O R decreases. We show that this counterintuitive behavior is related to the solid fraction, which depends on particle shape, and can be traced to purely geometrical characteristics such as coordination number and statistical particle orientation. Non-intuitively, the elongation of the particles does not influence the force distributions within the piles. • The AOR exhibits a non-monotonic behavior with particle elongation and friction. • Higher friction and greater elongation lead to an increase in AOR. • Critical particle elongation emerges at low friction, beyond which AOR declines.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it