Particle growth and shrinkage

Submitted by ullassssss on Mon, 05/30/2016 - 13:40

Can anyone comment the right syntax for particle growth and shrinkage problem. I need to increase the radius of 200000 particles from 100 micron 125 micron.

Thank you

Forums:

richti83's picture

richti83 | Tue, 05/31/2016 - 08:44

have a look at:
examples\LIGGGHTS\Tutorials_public\packing\in.packing

#calculate grow rate
variable Rgrowrate equal (${alphatarget}/${alphastart})^(${growevery}/(3.*${growts}))
print "The radius grow rate is ${Rgrowrate}"
#
#do the diameter grow
compute rad all property/atom radius
#
variable dgrown atom ${Rgrowrate}*2.*c_rad
fix grow all adapt ${growevery} atom diameter v_dgrown

I'm not an associate of DCS GmbH and not a core developer of LIGGGHTS®
ResearchGate | Contact

ullassssss | Tue, 05/31/2016 - 11:01

Thank you @richti83
#parameters for gradually growing particle diameter
variable alphastart equal 0.0001
variable alphatarget equal 0.000125
variable growts equal 50000
variable growevery equal 40
variable relaxts equal 20000

# Set the dumps
dump dmp all custom 10000 Ullas/shearcell/dump.1 id type type x y z ix iy iz vx vy vz fx fy fz &
omegax omegay omegaz radius
#dump dumpmesh all mesh/vtk 10000 Ullas/shearcell/dump*.vtk stress
#dump mov all movie 10000 Ullas/shearcell/movie.m4v type type size 1280 720

#calculate grow rate
variable Rgrowrate equal (${alphatarget}/${alphastart})^(${growevery}/(3.*${growts}))
print "The radius grow rate is ${Rgrowrate}"

#do the diameter grow
compute rad all property/atom radius

variable dgrown atom ${Rgrowrate}*2.*c_rad
fix grow all adapt ${growevery} atom diameter v_dgrown

#run
run ${growts}

#let the packing relax
unfix grow
run ${relaxts}

a part of my syntax is given above. How can i edit the particle growth rate? Since the given syntax doesnt give me complete growth in the stipulated time step

I need

tjleps | Thu, 04/18/2019 - 22:49

It's been a while since this was posted, however if anyone else comes across this looking for an answer, the problem was that the example script is for a desired volume fill, so it was cube rooted. For growing a diameter directly, remove the '3' in the denominator of the growrate formula exponent

dgluchinsky | Wed, 09/04/2019 - 21:25

Try DEMPack in KRATOS, mesh using spheres. Particle position and diameter can be exported in txt file and imported in LIGGGHTS using read_data