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@ -37,8 +37,8 @@ or <A HREF = "read_restart.html">read_restart</A> commands:
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</P>
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<UL><LI>R0 (distance)
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<LI>K2 (energy/distance^2)
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<LI>K3 (energy/distance^2)
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<LI>K4 (energy/distance^2)
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<LI>K3 (energy/distance^3)
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<LI>K4 (energy/distance^4)
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</UL>
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<P><B>Restrictions:</B>
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</P>
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@ -34,8 +34,8 @@ or "read_restart"_read_restart.html commands:
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R0 (distance)
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K2 (energy/distance^2)
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K3 (energy/distance^2)
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K4 (energy/distance^2) :ul
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K3 (energy/distance^3)
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K4 (energy/distance^4) :ul
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[Restrictions:]
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@ -173,6 +173,8 @@ viscous</A>, <A HREF = "fix_nvt.html">fix nvt</A>
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<P>The option defaults are axes = 1 1 1, scale = 1.0 for all types, no
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region, and weight = 1.0.
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</P>
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<HR>
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<A NAME = "Dunweg"></A>
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<P><B>(Dunweg)</B> Dunweg and Paul, Int J of Modern Physics C, 2, 817-27 (1991).
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@ -164,5 +164,7 @@ viscous"_fix_viscous.html, "fix nvt"_fix_nvt.html
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The option defaults are axes = 1 1 1, scale = 1.0 for all types, no
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region, and weight = 1.0.
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:line
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:link(Dunweg)
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[(Dunweg)] Dunweg and Paul, Int J of Modern Physics C, 2, 817-27 (1991).
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@ -24,7 +24,7 @@
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<LI>args = list of arguments for a particular style
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<PRE> <I>xplane</I> or <I>yplane</I> or <I>zplane</I> args = lo hi gamma xmu
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lo, hi = position of lower and upper plane (either can be NULL)
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lo,hi = position of lower and upper plane (distance units), either can be NULL)
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gamman = damping coeff for normal direction collisions with wall
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xmu = friction coeff for the wall
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<I>zcylinder</I> args = radius gamma xmu
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@ -34,11 +34,15 @@
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</PRE>
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<LI>zero or more keyword/value pairs may be appended to args
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<PRE> keyword = <I>wiggle</I>
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values = dim amplitude period
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dim = <I>x</I> or <I>y</I> or <I>z</I>
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amplitude = size of oscillation (distance units)
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period = time of oscillation (time units)
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<LI>keyword = <I>wiggle</I> or <I>shear</I>
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<PRE> <I>wiggle</I> values = dim amplitude period
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dim = <I>x</I> or <I>y</I> or <I>z</I>
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amplitude = size of oscillation (distance units)
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period = time of oscillation (time units)
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<I>shear</I> values = dim vshear
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dim = <I>x</I> or <I>y</I> or <I>z</I>
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vshear = magnitude of shear velocity (velocity units)
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</PRE>
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</UL>
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@ -62,20 +66,38 @@ axis is at x = y = 0.0, and the radius of the cylinder is specified.
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For all wallstyles, a damping and friction coefficient for
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particle-wall interactions are also specified.
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</P>
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<P>Optionally, a wall can be oscillated, similar to the oscillations of
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frozen particles specified by the <A HREF = "fix_wiggle.html">fix_wiggle</A>
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command. This is useful in packing simulations of granular particles.
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If the keyword <I>wiggle</I> is appended to the argument list, then a
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dimension for the motion, as well as it's <I>amplitude</I> and <I>period</I> is
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specified. Each timestep, the position of the wall in the appropriate
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<I>dim</I> is set according to this equation:
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<P>Optionally, the wall can be moving, if the <I>wiggle</I> or <I>shear</I>
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keywords are appended. Both keywords cannot be used together.
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</P>
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<P>For the <I>wiggle</I> keyword, the wall oscillates sinusoidally, similar to
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the oscillations of frozen particles specified by the
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<A HREF = "fix_wiggle.html">fix_wiggle</A> command. This is useful in packing
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simulations of granular particles. The arguments to the <I>wiggle</I>
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keyword specify a dimension for the motion, as well as it's
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<I>amplitude</I> and <I>period</I>. Note that if the dimension is in the plane
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of the wall, this is effectively a shearing motion. If the dimension
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is perpendicular to the wall, it is more of a shaking motion. A
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<I>zcylinder</I> wall can only be wiggled in the z dimension.
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</P>
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<P>Each timestep, the position of a wiggled wall in the appropriate <I>dim</I>
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is set according to this equation:
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</P>
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<PRE>position = pos0 + A - A cos (omega * delta)
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</PRE>
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<P>where <I>pos0</I> is the position at the time the fix was specified, <I>A</I> is
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the <I>amplitude</I>, <I>omega</I> is 2 PI / <I>period</I>, and <I>delta</I> is the
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elapsed time since the fix was specified. The velocity of the wall is
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also set to the derivative of this expression.
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set to the derivative of this expression.
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</P>
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<P>For the <I>shear</I> keyword, the wall moves continuously in the specified
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dimension with velocity <I>vshear</I>. The dimension must be tangential to
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walls with a planar <I>wallstyle</I>, e.g. in the <I>y</I> or <I>z</I> directions for
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an <I>xplane</I> wall. For <I>zcylinder</I> walls, a dimension of <I>z</I> means the
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cylinder is moving in the z-direction along it's axis. A dimension of
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<I>x</I> or <I>y</I> means the cylinder is spinning around the z-axis, either in
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the clockwise direction for <I>vshear</I> > 0 or counter-clockwise for
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<I>vshear</I> < 0. In this case, <I>vshear</I> is the tangential velocity of
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the wall at whatever <I>radius</I> has been defined.
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</P>
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<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
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</P>
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@ -102,8 +124,6 @@ LAMMPS</A> section for more info.
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</P>
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<P>Any dimension (xyz) that has a granular wall must be non-periodic.
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</P>
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<P>A zcylinder wall can only be oscillated in the z dimension.
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "fix_wiggle.html">fix_wiggle</A>
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@ -17,7 +17,7 @@ wall/gran = style name of this fix command :l
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style = {xplane} or {yplane} or {zplane} or {zcylinder} :l
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args = list of arguments for a particular style :l
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{xplane} or {yplane} or {zplane} args = lo hi gamma xmu
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lo, hi = position of lower and upper plane (either can be NULL)
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lo,hi = position of lower and upper plane (distance units), either can be NULL)
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gamman = damping coeff for normal direction collisions with wall
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xmu = friction coeff for the wall
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{zcylinder} args = radius gamma xmu
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@ -25,11 +25,14 @@ args = list of arguments for a particular style :l
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gamman = damping coeff for normal direction collisions with wall
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xmu = friction coeff for the wall :pre
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zero or more keyword/value pairs may be appended to args :l
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keyword = {wiggle}
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values = dim amplitude period
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dim = {x} or {y} or {z}
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amplitude = size of oscillation (distance units)
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period = time of oscillation (time units) :pre
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keyword = {wiggle} or {shear} :l
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{wiggle} values = dim amplitude period
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dim = {x} or {y} or {z}
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amplitude = size of oscillation (distance units)
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period = time of oscillation (time units)
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{shear} values = dim vshear
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dim = {x} or {y} or {z}
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vshear = magnitude of shear velocity (velocity units) :pre
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:ule
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[Examples:]
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@ -52,20 +55,38 @@ axis is at x = y = 0.0, and the radius of the cylinder is specified.
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For all wallstyles, a damping and friction coefficient for
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particle-wall interactions are also specified.
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Optionally, a wall can be oscillated, similar to the oscillations of
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frozen particles specified by the "fix_wiggle"_fix_wiggle.html
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command. This is useful in packing simulations of granular particles.
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If the keyword {wiggle} is appended to the argument list, then a
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dimension for the motion, as well as it's {amplitude} and {period} is
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specified. Each timestep, the position of the wall in the appropriate
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{dim} is set according to this equation:
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Optionally, the wall can be moving, if the {wiggle} or {shear}
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keywords are appended. Both keywords cannot be used together.
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For the {wiggle} keyword, the wall oscillates sinusoidally, similar to
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the oscillations of frozen particles specified by the
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"fix_wiggle"_fix_wiggle.html command. This is useful in packing
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simulations of granular particles. The arguments to the {wiggle}
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keyword specify a dimension for the motion, as well as it's
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{amplitude} and {period}. Note that if the dimension is in the plane
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of the wall, this is effectively a shearing motion. If the dimension
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is perpendicular to the wall, it is more of a shaking motion. A
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{zcylinder} wall can only be wiggled in the z dimension.
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Each timestep, the position of a wiggled wall in the appropriate {dim}
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is set according to this equation:
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position = pos0 + A - A cos (omega * delta) :pre
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where {pos0} is the position at the time the fix was specified, {A} is
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the {amplitude}, {omega} is 2 PI / {period}, and {delta} is the
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elapsed time since the fix was specified. The velocity of the wall is
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also set to the derivative of this expression.
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set to the derivative of this expression.
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For the {shear} keyword, the wall moves continuously in the specified
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dimension with velocity {vshear}. The dimension must be tangential to
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walls with a planar {wallstyle}, e.g. in the {y} or {z} directions for
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an {xplane} wall. For {zcylinder} walls, a dimension of {z} means the
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cylinder is moving in the z-direction along it's axis. A dimension of
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{x} or {y} means the cylinder is spinning around the z-axis, either in
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the clockwise direction for {vshear} > 0 or counter-clockwise for
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{vshear} < 0. In this case, {vshear} is the tangential velocity of
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the wall at whatever {radius} has been defined.
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[Restart, fix_modify, output, run start/stop, minimize info:]
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@ -92,8 +113,6 @@ LAMMPS"_Section_start.html#2_3 section for more info.
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Any dimension (xyz) that has a granular wall must be non-periodic.
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A zcylinder wall can only be oscillated in the z dimension.
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[Related commands:]
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"fix_wiggle"_fix_wiggle.html
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