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From: Егор Никитин <nickitineg@...567...>
Date: Fri, 13 Oct 2017 10:57:51 +0300

Hello, my name is Nikitin Egor, I am a student of the Rostov University of railway transport. At the moment I'm writing my thesis in which I use Lammps software product. I need to reproduce the simulation of friction between two surfaces between which the lubricant is present. Now I built two surfaces, but to place between the grease I have is the difficulty. Tell me how can I solve my problem? Code is attached below.
 
units        metal
boundary    p p s
 
atom_style    atomic
lattice        bcc 2.855324
region        box block 0 30.0 0 16.0 0 20.0
create_box    4 box
 
pair_style    eam/fs
pair_coeff    * * Fe_mm.eam.fs Fe Fe Fe Fe
 
neighbor    0.3 bin
neigh_modify    delay 5
 
region          lo-fixed block INF INF INF INF INF 1.8
region          lo-slab block INF INF INF INF INF 5.0
region          above-lo block INF INF INF INF INF 5.0 side out
region          hi-fixed block INF INF INF INF 18.2 INF
region          hi-slab block INF INF INF INF 15.0 INF
region          below-hi block INF INF INF INF 15.0 INF side out
 
create_atoms    1 region lo-slab
create_atoms    1 region hi-slab
 
group        lo region lo-slab
group        lo type 2
group        hi region hi-slab
group        hi type 3
group        lo-fixed region lo-fixed
group        hi-fixed region hi-fixed
group        boundary union lo-fixed hi-fixed
group        mobile subtract all boundary
 
set        group lo-fixed type 4
set        group hi-fixed type 4
 
# temp controllers
 
compute        new3d mobile temp
compute        new2d mobile temp/partial 0 1 1
 
# equilibrate
 
velocity    mobile create 300.0 5812775 temp new3d
fix        1 all nve
fix        2 boundary setforce 0.0 0.0 0.0
 
fix        3 mobile temp/rescale 10 300.0 300.0 10.0 1.0
fix_modify    3 temp new3d
 
thermo        200
thermo_modify    temp new3d
 
timestep    0.001
run        2000
 
# friction
 
velocity    hi-fixed set 0.05 0.0 0.0 sum yes
 
unfix        3
 
fix        3 mobile temp/rescale 10 450.0 450.0 10.0 1.0
fix_modify    3 temp new2d
 
dump        1 all atom 2000 dump.fe_nve
thermo        2000
thermo_modify    temp new2d
 
#reset_timestep    0
#run        4000