[lammps-users] Couette's flow with interaction

Hello,

I have a question,

when i simulate Couette's flow, i can see how atoms of flow interact with atoms of wall, but there are no interaction between atoms of wall, they're static and don't move.

What should i do to correct in my code if i want to simulate as interaction between flow and wall as interaction between atoms of walls.

Thanks a lot, Sergey R.

# 2-d LJ flow simulation

units lj
dimension 2
boundary p p p

atom_style atomic
neighbor 0.3 bin
neigh_modify delay 5

# create geometry

lattice hex 0.7
region box block 0 20 0 10 -0.25 0.25
create_box 2 box
create_atoms 1 box

mass 1 1.0
mass 2 1.0

# LJ potentials

pair_style lj/cut 1.12246
pair_coeff * * 1.0 1.0 1.12246

# define groups

region 1 block INF INF INF 1.25 INF INF
group lower region 1
group flow subtract all lower

set group lower type 2

# initial velocities

compute mobile flow temp
velocity flow create 1.0 482748 temp mobile
fix 1 all nve
fix 2 flow temp/rescale 200 1.0 1.0 0.02 1.0
fix_modify 2 temp mobile

# Couette flow

velocity lower set 0.0 0.0 0.0
fix 3 lower setforce 0.0 0.0 0.0
fix 4 flow addforce 0.3 0.0 0.0
fix 5 flow ave/spatial 10 100 1000 y 0.0 0.5 vx y ave running file vel.profile
fix 6 all enforce2d

# Run

timestep 0.003
thermo 100
thermo_modify temp mobile

dump 1 all atom 25 dump.flow.lammpstrj
run 10000

I'm not quite sure what the question is. But the way you use the setforce command will keep these atoms from moving due to interactions with any other atoms.
Matt

Quoting "Romashevsky S." <[email protected]>:

Don't set the force on the wall atoms to zero if you want them to respond
to interactions with the flow or each other.

Steve

03.05.2010 19:27, Matt K. Petersen пишет:

I'm not quite sure what the question is. But the way you use the setforce command will keep these atoms from moving due to interactions with any other atoms.
Matt

Quoting "Romashevsky S." <[email protected]>:

Hello,

I have a question,

when i simulate Couette's flow, i can see how atoms of flow interact
with atoms of wall, but there are no interaction between atoms of wall,
they're static and don't move.

What should i do to correct in my code if i want to simulate as
interaction between flow and wall as interaction between atoms of walls.

Thanks a lot, Sergey R.

# 2-d LJ flow simulation

units lj
dimension 2
boundary p p p

atom_style atomic
neighbor 0.3 bin
neigh_modify delay 5

# create geometry

lattice hex 0.7
region box block 0 20 0 10 -0.25 0.25
create_box 2 box
create_atoms 1 box

mass 1 1.0
mass 2 1.0

# LJ potentials

pair_style lj/cut 1.12246
pair_coeff * * 1.0 1.0 1.12246

# define groups

region 1 block INF INF INF 1.25 INF INF
group lower region 1
group flow subtract all lower

set group lower type 2

# initial velocities

compute mobile flow temp
velocity flow create 1.0 482748 temp mobile
fix 1 all nve
fix 2 flow temp/rescale 200 1.0 1.0 0.02 1.0
fix_modify 2 temp mobile

# Couette flow

velocity lower set 0.0 0.0 0.0
fix 3 lower setforce 0.0 0.0 0.0
fix 4 flow addforce 0.3 0.0 0.0
fix 5 flow ave/spatial 10 100 1000 y 0.0 0.5 vx y ave running file
vel.profile
fix 6 all enforce2d

# Run

timestep 0.003
thermo 100
thermo_modify temp mobile

dump 1 all atom 25 dump.flow.lammpstrj
run 10000

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________________________________________________
Dr. Matt K. Petersen,
Center for Biophysical Modeling and Simulation
and Department of Chemistry,
University of Utah
________________________________________________

ok, i just want that atoms of wall interact with each other like atoms of flow do.

Thanks a lot, Sergey R.