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A. Gladkyy, S. Roy, T. Weinhart, S. Luding, R. SchwarzeTU Bergakademie FreibergLampadiusstrasse 409599 FreibergGermany
DEM simulations ofweakly wetted granular materials:implementation of capillary bridge models
September 28-30, 2015, Barcelona, Spain
IV Conference on Particle-Based Methods, Particles 2015
TU Bergakademie Freiberg
Situated in the city of Freiberg, Saxony, Germany6 faculties, 5600 students, 86 professors2 collaborative research centersInstitute of Mechanics and Fluid Dynamics:
Applied Mechanics: Solid Mechanics, DynamicsFluid Mechanics, TurbomachineryNumerical modelling of granular flow processes:CFD, DEM, SPH
Source: https://commons.wikimedia.org/wiki/File:Weisbachbau_Freiberg_TU_Bergakademie.jpg2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 1
Discrete element model with capillary bridges
jω
ωi
rj
v j
ri
v i
R
R
lijc
mPd⃗vdt =
∑c
f⃗c + mPg⃗
IPdω⃗dt =
∑c
(⃗lc × f⃗c
)
f⃗n =
(−knδn − γn
dδndt + fcap
)n̂
f⃗t = min[−ktδt − γt
dδtdt , µfn
]t̂
S+ =a
2√
V/R
fcap =2πRγ cos θ
1 + 2.1(S+) + 10(S+)2Willett formulation(see Gladkyy, Schwarze 2014 for details)
Ri Rj
β
R1
R2
a
Θ
dsp/sp
α
i j
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 2
Split-bottom shear cell configuration
Fig. 1: Setup of split-bottom configuration (see Gladkyy, Schwarze 2014 for details)
DEM parameters
Dp = 2.2 mm; ρ = 2000 kg m−3; kn = 110 N m−1; kt = 12 N m−1;γn = 0.002 kg s−1; γt = 0.0005 kg s−1; θ = 20°; γ = 20.6 mN m−1;Particle number ≈ 145000; Rotation 0.6 RPM; Vb =0 nl to 200 nl;
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 3
DEM open-source software
MercuryDPM, YADE, LIGGGHTS
Computational parts are written in C++, running on Linux/UnixParallelization (MPI, OpenMP)Free GPL (v. 2 and v. 3) licensesData export into different formats, including VTKReach functions for work with complex geometriesParticle import/export and generation opportunitiesAvailable in Debian/Ubuntu repositories (YADE, LIGGGHTS)CMake build system
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 4
DEM open-source software
MercuryDPM: http://mercurydpm.org
C++ for the simulation setup and scenarioContributors: University of Twente (The Netherlands), community
Yet Another Dynamic Engine (YADE): http://yade-dem.org
Python bindings for simulation setup, control and postprocessingOpenMP; GUI for simulation setup and controlContributors: community (Lab 3SR - Grenoble, CTU Prague, TU Freiberg …)
LIGGGHTS (LAMMPS improved for general granular and granular heat transfer simulations): http://liggghts.com
Own scripting language for simulation setupMPI; coupling with CFD-code, SPH-model, heat-transferContributors: DCS Computing, community (TU Graz, JKU Linz …)
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 5
Implementation of capillary bridge models
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 6
Velocity profile compare
0
0.2
0.4
0.6
0.8
1
20 30 40 50 60 70 80 90 100 110
ω/ω
0 [-
]
r [mm]
MercuryDPMYade
Liggghts
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 7
Contact number probability
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 2 4 6 8 10
Pro
babi
lity
[-]
Contact number [-]
MercuryDPMYade
Liggghts
0 4 8 12 16
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 8
Water content
0.01
0.1
1
10
0 50 100 150 200
Wat
er c
onte
nt [%
]
Bridge volume [nl]
MercuryDPMYade
Liggghts
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 9
Conclusions
Good practice in writing open-source programs
Before starting a new program, try to join existing project.Do not invent your own license (DFSG).Only source files in the tarball, build everything from source.Avoid inclusion of 3rd-party codes.Document dependencies.Use proper versioning and prepare releases.Have an automatic test suit.Use build system: autoconf and automake, cmake.
https://wiki.debian.org/UpstreamGuide
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 10
Thank you for your attention!
2015-09-{28…30}PARTICLES 2015
Gladkyy, Roy, Weinhart, Luding, Schwarze IMFDTU Bergakademie Freiberg 11