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lammps/doc/src/fix_lb_momentum.txt
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fix_lb_momentum.txt
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
:line
fix lb/momentum command :h3
[Syntax:]
fix ID group-ID lb/momentum nevery keyword values ... :pre
ID, group-ID are documented in the "fix"_fix.html command :ulb,l
lb/momentum = style name of this fix command :l
nevery = adjust the momentum every this many timesteps :l
zero or more keyword/value pairs may be appended :l
keyword = {linear} :l
{linear} values = xflag yflag zflag
xflag,yflag,zflag = 0/1 to exclude/include each dimension. :pre
:ule
[Examples:]
fix 1 sphere lb/momentum
fix 1 all lb/momentum linear 1 1 0 :pre
[Description:]
This fix is based on the "fix momentum"_fix_momentum.html command, and
was created to be used in place of that command, when a
lattice-Boltzmann fluid is present.
Zero the total linear momentum of the system, including both the atoms
specified by group-ID and the lattice-Boltzmann fluid every nevery
timesteps. This is accomplished by adjusting the particle velocities
and the fluid velocities at each lattice site.
NOTE: This fix only considers the linear momentum of the system.
By default, the subtraction is performed for each dimension. This can
be changed by specifying the keyword {linear}, along with a set of
three flags set to 0/1 in order to exclude/ include the corresponding
dimension.
[Restart, fix_modify, output, run start/stop, minimize info:]
No information about this fix is written to "binary restart
files"_restart.html. None of the "fix_modify"_fix_modify.html options
are relevant to this fix. No global or per-atom quantities are stored
by this fix for access by various "output
commands"_Section_howto.html#howto_15. No parameter of this fix can be
used with the {start/stop} keywords of the "run"_run.html command.
This fix is not invoked during "energy minimization"_minimize.html.
[Restrictions:]
Can only be used if a lattice-Boltzmann fluid has been created via the
"fix lb/fluid"_fix_lb_fluid.html command, and must come after this
command.
This fix is part of the USER-LB package. It is only enabled if LAMMPS
was built with that package. See the "Making
LAMMPS"_Section_start.html#start_3 section for more info.
[Related commands:]
"fix momentum"_fix_momentum.html, "fix lb/fluid"_fix_lb_fluid.html
[Default:]
Zeros the total system linear momentum in each dimension.
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