Hello everybody,
I hope not to bother you too much with this, but i'm in some kind of dead end. I simply don't know whats going wrong. I'va made a little example to get used to the Liggghts features (see below). A 1*1*1 Box with particles falling in z direction and a pyramid structure at the bottom. The particles should fall against the sides of the pyramid and roll down. but instead they just ignore the pyramid and land on the lower wall of the box.
Would be great if you could point out my mistake (I am pretty shure there is one)
Regards,
Martin Koester
pyramid structure:
http://www.yrthy.de/pyr.jpg
input file:
dimension 3
atom_style granular
boundary m m m
newton off
atom_modify sort 0 0
communicate single vel yes
units si
timestep 0.000001
region reg block 0 1 0 1 0 1 units box
region re2 block 0.1 0.9 0.1 0.9 0.85 0.9 units box
create_box 1 reg
lattice sc 0.05
create_atoms 1 region re2
set region reg density 750
set region reg diameter 0.001
neighbor 0.002 bin
neigh_modify delay 0
pair_style gran/hooke/history 1 0
pair_coeff * *
fix 1 all nve/sphere
fix 2 all gravity 9.81 vector 0.0 0.0 -1.0
fix cad1 all mesh/gran pyr.stl 1 1 0 0 0 0 0 0
fix boxwalls_x all wall/gran/hooke/history 1 0 xplane 0 1 1
fix boxwalls_y all wall/gran/hooke/history 1 0 yplane 0 1 1
fix boxwalls_z all wall/gran/hooke/history 1 0 zplane 0 1 1
fix pyramid_wall all wall/gran/hooke/history 1 0 mesh/gran 1 cad1
fix m1 all property/global youngsModulus peratomtype 5.e6
fix m2 all property/global poissonsRatio peratomtype 0.45
fix m3 all property/global coefficientRestitution peratomtypepair 1 0.25
fix m4 all property/global coefficientFriction peratomtypepair 1 0.25
fix m5 all property/global characteristicVelocity scalar 2.
fix m6 all property/global cohesionEnergyDensity peratomtypepair 1 10
compute str all stress/atom
thermo_style custom step atoms cpu etotal
thermo 5000
dump id all custom 1000 ham_01.lammpstrj id type x y z vx vy vz
dump ie all xyz 1000 bin/ham_01.*.xyz
dump st all stl 1000 stl/ham_01.*.stl
dump d0 all custom 100 dump.1 id id type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius
run 1000000
STL-file:
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endsolid AutoCAD
ckloss | Fri, 05/14/2010 - 13:12
Re: Whats wrong with my mesh/gran simulation
At first glance, the neighbor setup is not really optimal for this problem, and the time-step is short, both of which will slow down the sim considerably. But the geometry should be recognized anyway. I'll have a look.
Christoph
ckloss | Mon, 05/17/2010 - 15:39
Re: Re: Whats wrong with my mesh/gran simulation
Hi Martin,
Thanks for the report. I had a closer look at your input script.
This is related to a known issue that will be fixed in version 1.0.2, to be released by the end of this week.
For now, you can solve the problem by replacing
run 1000000
by
run 1
run 1000000 upto
That should do it. Btw, neighbor setup for your problem is sub-optimal. There is speed-up potential of factor 100 for your simulation by varying the neigh list params.
Hope I could help,
Christoph
mkoester | Mon, 05/17/2010 - 16:02
Thanks for your answer, i'll
Thanks for your answer, i'll try it ASAP.
What range would you suggest for the neigh list parameters?
thanks a lot,
martin
ckloss | Mon, 05/17/2010 - 16:11
neigh list
Hi Martin,
try experimenting with skin distance and binsize. You can choose binsize seperately via neigh_modify; it should be much larger that chosen in your script, e.g. 0.02
Christoph