[lammps-users] Some issues in fix/wall/gran using cylindrical wall

Dear all,

I am trying to simulate one particle motion in a rotating cylindrical tube. The input is given through read_data command. What I observed is that when I drop a particle from the cylinder center to the curved surface (not axially), its interaction with the wall gives “nan” in the output file in position and energy values after the particle reaches the cylindrical wall. But, before that, when particle is away from the wall, the output file gives finite values. I don’t know what is happening. Please guide me on this issue.



For reference, input file parameters are:

dimension 3
atom_style granular
boundary f f f
newton off

neighbor 0.2 bin
neigh_modify delay 0
communicate single vel yes

read_data initconfig.dat
pair_style gran/hooke/history 100000.0 0.0 64.0 64.0 0.5 1
pair_coeff * *

timestep 0.0001

fix integ all nve/sphere
fix grav1 all gravity 1.0 spherical -90.0 90.0
fix cylwall all wall/gran 100000.0 0.0 64.0 64.0 0.5 1 &
zcylinder 5.5 shear y -5.0
compute 1 all erotate/sphere
compute 2 all ke
thermo_style custom step atoms ke c_2 c_1
thermo 1000
thermo_modify lost error norm no
compute_modify thermo_temp dynamic yes
dump 1 all custom 100 pos_coord.dat id type x y z
run 100000

The input configuration file is:

1 atoms

1 atom types

-5.5000000000000 5.5000000000000 xlo xhi
-5.5000000000000 5.5000000000000 ylo yhi
0.000000000000000E+000 10.0000000000000 zlo zhi


1 1 1.00000000 1.00000000 0.0 -4.50 5.0

1 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000

I don't know. Have you visuzlized the system
and dumped atom coords on a fine time scale to
insure the atom is where you think it should be?