[lammps-users] fix move

Dear lammps-users,

I tried to simulate couette flow with fix move command. Unfortunately, the fluid atoms confined between the parallel walls under shear penetrated through the wall and the fluid’s temperature was increasing from 1.0 to 1.2 or more (LJ unit). The script after equilibrium simulation is as following:

units lj
dimension 3
boundary p p s
atom_style full
neighbor 0.3 bin
neigh_modify delay 5

read_restart restart.1000000

pair_style lj/cut 3.0
pair_coeff ! 1 1 4 1 3.0
pair_coeff 1 2 2 1 3.0
pair_coeff 2 2 1 1 3.0
pair_modify shift yes

restart 1000000 restart.*
compute boun boundary temp
compute boun2 boundary temp/profile 0 1 1 z 4
compute mobile flow temp
compute mobile2 flow temp/profile 0 1 1 z 4
compute 3 all stress/atom

fix 1 flow nve
fix&nb! sp; & nbsp; 8 upper move linear 0.3 NULL NULL units box
fix 9 lower move linear -0.3 NULL NULL units box
fix 2 boundary temp/rescale 1 1.0 1.0 0.02 1.0
fix_modify 2 temp boun2
fix 14 all ave/spatial 200 1000 200000 z center 1 density/mass density/number vx vy vz c_3[5] ave window 25 file ds-1.file units box

thermo_style custom step temp press pe ke etotal vol c_boun2
thermo 5000
thermo_modify temp mobile2
timestep 0.005
dump &n! bsp; 1 all custom 100000 dump.lammpstrj id type x y z vx vy vz
run 40000000

Any comment is appreciated!



This could be for a number of reasons, not due to
LAMMPS, but to how you have setup your model.
No one is likely to debug your script for you. If you
have a question about how a specific LAMMPS command
is working, then you will likely get a better response.

Also, you can look at examples/flow/in.flow.couette for
a simple script that does Couette flow, w/out fix move.