This command moves node coordinates in the following manner.
Three pairs of random numbers between 0 and 1 are generated. These pairs refer to the x, y and z coordinates of the nodes respectively. The first random number of each pair is multiplied by the factor given in the command. The second random number is used to determine if the calculated offset is to be added or subtracted from the coordinate.
WARNING: No checking is done to see if elements are inverted by this
perturbation. If one uses too large a value for the perturbation, one
can easily cause element inversions that will flip the normal vector of
triangles and cause 3D cells to have negative volumes.
Use the QUALITY command to report element volumes.
perturb/ pset,get,psetname / xfactor,yfactor,zfactor
pset,get,psetname is the range of nodes to offset, 1,0,0 means all nodes.
xfactor,yfactor,zfactor perturbation values
perturb/1,0,0/0.5,0,0
add offsets to only the xcoordinates of all nodes
perturb/pset,get,mypset/0.001,0.001,0.001
add small offsets to all coordinates of the nodes in the pset named mypset
# For a unit cell divided into PTS**3 sub-cells,
# delta-x = 0.01 = distance between sub-cell centers
# x_p = delta-x / 100 = 0.0001 = 1% perturbations
# eps_1 = sqrt(3*x_p) = 0.000173 = max dist. from origin
define/XP/0.0001
define/EPS1/0.00018
define/PTS/101
cmo/create/mo1
createpts/xyz/PTS,PTS,PTS/0.,0.,0./1.,1.,1./1,1,1/
pset/po1/seq/0,0,0/
cmo/setatt/mo1/imt/pset,get,po1/1
cmo/create/mo2
createpts/xyz/PTS,PTS,PTS/0.,0.,0./1.,1.,1./1,1,1/
pset/po2/seq/0,0,0/
cmo/setatt/mo2/imt/pset,get,po2/2
perturb/pset,get,po2/XP,XP,XP/
addmesh/merge/mfilter/mo1/mo2
cmo/copy/mfilterkd/mfilter
cmo/select/mfilter
filter/1 0 0/EPS1
cmo/printatt/mfilter/imt/minmax
cmo/printatt/mfilter/-xyz-/minmax
cmo/select/mfilter
rmpoint/compress
cmo/printatt/mfilter/imt/minmax
cmo/printatt/mfilter/-xyz-/minmax
finish