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<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>
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<H3>fix smd/move_tri_surf command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>fix ID group-ID smd/move_tri_surf keyword
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
<LI>smd/move_tri_surf keyword = style name of this fix command
<LI>keyword = <I>*LINEAR</I> or <I>*WIGGLE</I> or <I>*ROTATE</I>
<PRE> <I>*LINEAR</I> args = Vx Vy Vz
Vx,Vy,Vz = components of velocity vector (velocity units), any component can be specified as NULL
<I>*WIGGLE</I> args = Vx Vy Vz max_travel
vx,vy,vz = components of velocity vector (velocity units), any component can be specified as NULL
max_travel = wiggle amplitude
<I>*ROTATE</I> args = Px Py Pz Rx Ry Rz period
Px,Py,Pz = origin point of axis of rotation (distance units)
Rx,Ry,Rz = axis of rotation vector
period = period of rotation (time units)
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>fix 1 tool smd/move_tri_surf *LINEAR 20 20 10
fix 2 tool smd/move_tri_surf *WIGGLE 20 20 10
fix 2 tool smd/move_tri_surf *ROTATE 0 0 0 5 2 1
</PRE>
<P><B>Description:</B>
</P>
<P>This fix applies only to rigid surfaces read from .STL files via fix <A HREF = "fix_smd_wall_surface.html">smd/wall_surface</A> .
It updates position and velocity for the particles in the group each timestep without regard to forces on the particles.
The rigid surfaces can thus be moved along simple trajectories during the simulation.
</P>
<P>The <I>*LINEAR</I> style moves particles with the specified constant velocity
vector V = (Vx,Vy,Vz). This style also sets the velocity of each particle
to V = (Vx,Vy,Vz).
</P>
<P>The <I>*WIGGLE</I> style moves particles in an oscillatory fashion.
Particles are moved along (vx, vy, vz) with constant velocity until a
displacement of max_travel is reached. Then, the velocity vector is
reversed. This process is repeated.
</P>
<P>The <I>*ROTATE</I> style rotates particles around a rotation axis R = (Rx,Ry,Rz) that
goes through a point P = (Px,Py,Pz). The period of the rotation is also
specified. This style also sets the velocity of each particle to (omega cross
Rperp) where omega is its angular velocity around the rotation axis and
Rperp is a perpendicular vector from the rotation axis to the particle.
</P>
<P>See <A HREF = "USER/smd/SMD_LAMMPS_userguide.pdf">this PDF guide</A> to using Smooth Mach Dynamics in LAMMPS.
</P>
<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
</P>
<P>Currently, no part of USER-SMD supports restarting nor minimization. This fix has no outputs.
</P>
<P><B>Restrictions:</B>
</P>
<P>This fix is part of the USER-SMD 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><B>Related commands:</B>
</P>
<P><A HREF = "compute_smd_triangle_mesh_vertices.html">smd/triangle_mesh_vertices</A>, <A HREF = "fix_smd_wall_surface.html">smd/wall_surface</A>
</P>
<P><B>Default:</B> none
</P>
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