Hi! everyone
I have some problems with the simulation of particle collision using the Jan10 version with GRANULAR packages. I did a quite simple systems comprised of just two sphere particles with a diameter of 0.004m. The initial separation between the two particles is set to 0.01m. The I have one of them move towards the other with the velocity of 100m/s, monitering the variations of their velocities, locations and contact forces. A pretty odd thing came out. If I employed the gran/hertz/history pair style, the moving particle seemed to move with a nearly constant velocity (~100m/s) all the way, even passing through the initial static particle, the latter remaining almost stationary all the time. I have attached the input script and part of dump file as the following.
I’d much appreciate your help!
Example: Collision of two particles
#define particle style
atom_style granular
communicate single vel yes
newton off
#set simulation domain boundaries
boundary m m m
#setting SI units and define simulation region
units si
lattice sc 0.1
region mybox block -0.1 0.1 -0.1 0.1 -0.1 0.1 units box
create_box 2 mybox
create_atoms 2 single 0 0 0
create_atoms 2 single 0.1 0 0
set atom 1 type 1 vx 100 diameter 0.004 density 8000
set atom 2 type 2 diameter 0.04 density 8000
#settings for neighbor list
neighbor 0.002 bin
pair_style gran/hertz/history 2.e5 NULL 50.0 NULL 0.5 0
pair_coeff * *
fix integr all nve/sphere
#compute attribute_atom all property/atom x vx vy fx fy
timestep 0.0000001
thermo_style custom step ke etotal
thermo 10
dump 1 all custom 100 attribute_collision id x vx fx
run 1500
#dump file containing the temperal variation of particles’ location(x coordinate), velocity (vx) and normal contact force (Fx)
ITEM: TIMESTEP
0
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0 100 -11.2166
2 0.01 0 11.2166
ITEM: TIMESTEP
500
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.00493633 97.2173 -18.8037
2 0.0100001 0.00278269 18.8037
ITEM: TIMESTEP
800
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.00781853 94.836 -23.8007
2 0.0100002 0.00516403 23.8007
ITEM: TIMESTEP
1200
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.0115632 94.2449 24.9085
2 0.0100004 0.00575506 -24.9085
ITEM: TIMESTEP
1300
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.0125102 95.1421 23.1972
2 0.0100005 0.00485792 -23.1972
ITEM: TIMESTEP
1400
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.0134658 95.9759 21.5118
2 0.0100005 0.00402414 -21.5118
ITEM: TIMESTEP
1500
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.0144295 96.7473 19.8558
2 0.0100006 0.00325269 -19.8558
ITEM: TIMESTEP
1600
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.0154006 97.4576 18.2323
2 0.0100006 0.00254242 -18.2323
ITEM: TIMESTEP
1700
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.0163784 98.108 16.6448
2 0.0100006 0.00189205 -16.6448
ITEM: TIMESTEP
1800
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
1 0.0173625 98.6998 15.0966
2 0.0100006 0.00130016 -15.0966
ITEM: TIMESTEP
1810
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
2 0.0100006 0.00124414 -14.9441
1 0.0174613 98.7559 14.9441
ITEM: TIMESTEP
1820
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
2 0.0100006 0.00118867 -14.792
1 0.01756 98.8113 14.792
ITEM: TIMESTEP
1830
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
2 0.0100006 0.00113378 -14.6404
1 0.0176589 98.8662 14.6404
ITEM: TIMESTEP
1840
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
2 0.0100006 0.00107945 -14.4892
1 0.0177578 98.9205 14.4892
ITEM: TIMESTEP
1850
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
2 0.0100006 0.00102569 -14.3384
1 0.0178567 98.9743 14.3384
ITEM: TIMESTEP
1860
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
2 0.0100006 0.000972481 -14.1881
1 0.0179557 99.0275 14.1881
ITEM: TIMESTEP
1870
ITEM: NUMBER OF ATOMS
2
ITEM: BOX BOUNDS
-0.1 0.1
-0.1 0.1
-0.1 0.1
ITEM: ATOMS id x vx fx
2 0.0100006 0.000919837 -14.0382
1 0.0180548 99.0802 14.0382