LIGGGHTS WWW Site - LIGGGHTS Documentation - LIGGGHTS Commands
Syntax:
fix ID group-ID move/mesh/gran style args keyword values meshgran_id ssf
ID, group-ID are documented in fix command
move = style name of this fix command
style = linear or wiggle or riggle or rotate or variable
linear args = Vx Vy Vz Vx,Vy,Vz = components of velocity vector (velocity units), any component can be specified as NULL wiggle args = Ax Ay Az period Ax,Ay,Az = components of amplitude vector (distance units), any component can be specified as NULL period = period of oscillation (time units) rotate 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)
riggle args = Px Py Pz Rx Ry Rz period amplitude
Px,Py,Pz = origin point of axis of rotation (distance units) Rx,Ry,Rz = axis of rotation vector (radians)
period = period of oscillation (time units) amplitude = amplitude of rotational oscillation (in variable args = v_dx v_dy v_dz v_vx v_vy v_vz v_dx,v_dy,v_dz = 3 variable names that calculate x,y,z displacement as function of time, any component can be specified as NULL v_vx,v_vy,v_vz = 3 variable names that calculate x,y,z velocity as function of time, any component can be specified as NULL
zero or more keyword/value pairs may be appended
keyword = units
units value = box
meshgran_id = id for the fix mesh/gran that the fix move/mesh/gran is applied to
ssf = a skin safety factor (no longer used)
Examples:
fix movecad all move/mesh/gran linear -0.5 0. -0.3 cad 1.0
LIGGGHTS vs. LAMMPS Info:
This command is not available in LAMMPS.
Description:
The mesh imported by the fix mesh/gran with the given id is moved. For details on the styles and their args, see fix move . Argument meshgran_id is the fix id of the fix of type fix mesh/gran that holds the STL data for the triangles to be moved. The skin safety factor ssf input is no longer used (it is determined automatically).
NOTE: If a dangerous tri neighbor list build is detected, this may be due to the fact that the geometry is moved too close to a region where particle insertion is taking place so that initial interpenetration happens when the particles are inserted.
NOTE: When moving a triangle, not only the node positions are moved but also a couple of other vectors. So moving one triangle is roughly as costly as moving 11 particles. The current implementation is effectively serial, which may lead to performance issues for very large geometries
IMPORTANT NOTE: For periodic boundaries, the STL mesh is NOT mapped.
Restart, fix_modify, output, run start/stop, minimize info:
This fix writes the original coordinates of moving triangles to binary restart files, so that the motion can not directly be continued in a restarted simulation. None of the fix_modify options are relevant to this fix. No parameter of this fix can be used with the start/stop keywords of the run command. This fix is not invoked during energy minimization.
Restrictions:
This fix automatically assumes 'units box', 'units lattice' is not possible . The current implementation is effectively serial, which may lead to performance issues for very large geometries .
Related commands:
Default: units = box