Granular boundary layer induces drilling nonlinearity
(2026) In Powder Technology 474.- Abstract
Cohesionless loose granular material (CLGM), defined by the absence of interparticle cohesion and a fragile packing structure, are highly sensitive to mechanical disturbances and exhibit fluid-like dynamics under shear. This study investigates the nonlinear behavior arising from the interaction between an auger drill and CLGM through a combination of laboratory experiments and discrete element method (DEM) simulations. We uncover a rotation-induced granular boundary layer—a dynamically evolving fluidized region surrounding the drill and sharply separated from the surrounding solid-like matrix. This boundary layer governs stress transmission and flow morphology, leading to strong deviations from classical quasi-hydrostatic stress... (More)
Cohesionless loose granular material (CLGM), defined by the absence of interparticle cohesion and a fragile packing structure, are highly sensitive to mechanical disturbances and exhibit fluid-like dynamics under shear. This study investigates the nonlinear behavior arising from the interaction between an auger drill and CLGM through a combination of laboratory experiments and discrete element method (DEM) simulations. We uncover a rotation-induced granular boundary layer—a dynamically evolving fluidized region surrounding the drill and sharply separated from the surrounding solid-like matrix. This boundary layer governs stress transmission and flow morphology, leading to strong deviations from classical quasi-hydrostatic stress profiles and inducing depth-dependent nonlinearities in drilling resistance. Our results show that conventional similarity criteria, which rely on geometric trajectory matching and are effective in cohesive granular materials, fail in CLGM. This failure stems from neglecting the granular boundary layer, whose thickness and rheology evolve with rotation speed. By incorporating this rate-dependent mechanism into a revised scaling framework, we identify a new dimensionless number that governs the nonlinear drilling response. The scaling reveals transitions in drilling dynamics, reflecting the onset of rheology-dominated regimes and delineating the boundary between efficient drilling and choking. Beyond advancing the fundamental physics of intruder-granular interactions, these findings provide guiding principles for practical applications, including planetary surface sampling, subsurface exploration, and granular materials transport in industrial processes.
(Less)
- author
- Huang, Shuo LU ; Liu, Zhenning ; Li, Yong LU and Liu, Caishan
- organization
- publishing date
- 2026-05
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Cohesionless loose granular material, Drilling nonlinearity, Experiments, Granular boundary layer, Simulations
- in
- Powder Technology
- volume
- 474
- article number
- 122306
- publisher
- Elsevier
- external identifiers
-
- scopus:105030925149
- ISSN
- 0032-5910
- DOI
- 10.1016/j.powtec.2026.122306
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: Copyright © 2026. Published by Elsevier B.V.
- id
- 0e803aba-6559-4245-8912-3cbf31048da1
- date added to LUP
- 2026-04-16 16:59:54
- date last changed
- 2026-04-16 17:10:59
@article{0e803aba-6559-4245-8912-3cbf31048da1,
abstract = {{<p>Cohesionless loose granular material (CLGM), defined by the absence of interparticle cohesion and a fragile packing structure, are highly sensitive to mechanical disturbances and exhibit fluid-like dynamics under shear. This study investigates the nonlinear behavior arising from the interaction between an auger drill and CLGM through a combination of laboratory experiments and discrete element method (DEM) simulations. We uncover a rotation-induced granular boundary layer—a dynamically evolving fluidized region surrounding the drill and sharply separated from the surrounding solid-like matrix. This boundary layer governs stress transmission and flow morphology, leading to strong deviations from classical quasi-hydrostatic stress profiles and inducing depth-dependent nonlinearities in drilling resistance. Our results show that conventional similarity criteria, which rely on geometric trajectory matching and are effective in cohesive granular materials, fail in CLGM. This failure stems from neglecting the granular boundary layer, whose thickness and rheology evolve with rotation speed. By incorporating this rate-dependent mechanism into a revised scaling framework, we identify a new dimensionless number that governs the nonlinear drilling response. The scaling reveals transitions in drilling dynamics, reflecting the onset of rheology-dominated regimes and delineating the boundary between efficient drilling and choking. Beyond advancing the fundamental physics of intruder-granular interactions, these findings provide guiding principles for practical applications, including planetary surface sampling, subsurface exploration, and granular materials transport in industrial processes.</p>}},
author = {{Huang, Shuo and Liu, Zhenning and Li, Yong and Liu, Caishan}},
issn = {{0032-5910}},
keywords = {{Cohesionless loose granular material; Drilling nonlinearity; Experiments; Granular boundary layer; Simulations}},
language = {{eng}},
publisher = {{Elsevier}},
series = {{Powder Technology}},
title = {{Granular boundary layer induces drilling nonlinearity}},
url = {{http://dx.doi.org/10.1016/j.powtec.2026.122306}},
doi = {{10.1016/j.powtec.2026.122306}},
volume = {{474}},
year = {{2026}},
}