forked from lijiext/lammps
101 lines
3.8 KiB
HTML
101 lines
3.8 KiB
HTML
<HTML>
|
|
<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
|
|
</CENTER>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
<H3>fix lb/viscous command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>fix ID group-ID lb/viscous
|
|
</PRE>
|
|
<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
|
|
<LI>lb/viscous = style name of this fix command
|
|
</UL>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<P>fix 1 flow lb/viscous
|
|
</P>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>This fix is similar to the <A HREF = "fix_viscous.html">fix viscous</A> command, and
|
|
is to be used in place of that command when a lattice-Boltzmann fluid
|
|
is present, and the user wishes to integrate the particle motion using
|
|
one of the built in LAMMPS integrators.
|
|
</P>
|
|
<P>This fix adds a force, F = - Gamma*(velocity-fluid_velocity), to each
|
|
atom, where Gamma is the force coupling constant described in the <A HREF = "fix_lb_fluid.html">fix
|
|
lb/fluid</A> command (which applies an equal and
|
|
opposite force to the fluid).
|
|
</P>
|
|
<P>IMPORTANT NOTE: This fix should only be used in conjunction with one
|
|
of the built in LAMMPS integrators; it should not be used with the
|
|
<A HREF = "fix_lb_pc.html">fix lb/pc</A> or <A HREF = "fix_lb_rigid_pc_sphere.html">fix
|
|
lb/rigid/pc/sphere</A> integrators, which
|
|
already include the hydrodynamic forces. These latter fixes should
|
|
only be used if the force coupling constant has been set by the user
|
|
(instead of using the default value); if the default force coupling
|
|
value is used, then this fix provides the only method for adding the
|
|
hydrodynamic forces to the particles.
|
|
</P>
|
|
<HR>
|
|
|
|
<P>For further details, as well as descriptions and results of several
|
|
test runs, see <A HREF = "#Mackay">Mackay et al.</A>. Please include a citation to
|
|
this paper if this fix is used in work contributing to published
|
|
research.
|
|
</P>
|
|
<HR>
|
|
|
|
<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
|
|
</P>
|
|
<P>As described in the <A HREF = "fix_viscous.html">fix viscous</A> documentation:
|
|
</P>
|
|
<P>"No information about this fix is written to <A HREF = "restart.html">binary restart
|
|
files</A>. None of the <A HREF = "fix_modify.html">fix_modify</A> options
|
|
are relevant to this fix. No global or per-atom quantities are stored
|
|
by this fix for access by various <A HREF = "Section_howto.html#howto_15">output
|
|
commands</A>. No parameter of this fix can
|
|
be used with the <I>start/stop</I> keywords of the <A HREF = "run.html">run</A> command.
|
|
</P>
|
|
<P>The forces due to this fix are imposed during an energy minimization,
|
|
invoked by the <A HREF = "minimize.html">minimize</A> command. This fix should only
|
|
be used with damped dynamics minimizers that allow for
|
|
non-conservative forces. See the <A HREF = "min_style.html">min_style</A> command
|
|
for details."
|
|
</P>
|
|
<P><B>Restrictions:</B>
|
|
</P>
|
|
<P>This fix is part of the USER-LB package. It is only enabled if LAMMPS
|
|
was built with that package. See the <A HREF = "Section_start.html#start_3">Making
|
|
LAMMPS</A> section for more info.
|
|
</P>
|
|
<P>Can only be used if a lattice-Boltzmann fluid has been created via the
|
|
<A HREF = "fix_lb_fluid.html">fix lb/fluid</A> command, and must come after this
|
|
command.
|
|
</P>
|
|
<P>This fix should not be used if either the <A HREF = "fix_lb_pc.html">fix lb/pc</A>
|
|
or <A HREF = "fix_lb_rigid_pc_sphere.html">fix lb/rigid/pc/sphere</A> integrator is
|
|
used.
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "fix_lb_fluid.html">fix lb/fluid</A>, <A HREF = "fix_lb_pc.html">fix lb/pc</A>, <A HREF = "fix_lb_rigid_pc_sphere.html">fix
|
|
lb/rigid/pc/sphere</A>
|
|
</P>
|
|
<P><B>Default:</B> none
|
|
</P>
|
|
<HR>
|
|
|
|
<A NAME = "Mackay"></A>
|
|
|
|
<P><B>(Mackay et al.)</B> Mackay, F. E., Ollila, S.T.T., and Denniston, C., Hydrodynamic Forces Implemented into LAMMPS through a lattice-Boltzmann fluid, Computer Physics Communications 184 (2013) 2021-2031.
|
|
</P>
|
|
</HTML>
|