cone-style insert region

Submitted by strakakl on Thu, 10/21/2010 - 19:04

Hi LIGGGHTS Users,

we try to create a cone-style insert region (just like a hopper) with the pour/dev/packing command. The input script looks like this:

#particle insertion region
region ins_cone cone z 0.04 0.0 0.01 0.065 0.09 0.16 units box
region ins_cyl cylinder z 0.04 0.0 0.065 0.08 0.16 units box
region no_ins_region intersect 2 ins_cyl ins_cone side out units box

...

#region and insertion
fix ins all pour/dev/packing 1 distributiontemplate pdd vol ${alphastart} 10 overlapcheck no region ins_cyl regionexempts 1 no_ins_region

The resulting geometry for insertion should be a cone, we think, but the particles are inserted in the "ins_cyl" except the cone. Any suggestions what's wrong in our input script?

cheers,

Klaus & Michael

Forums:

ckloss's picture

ckloss | Thu, 10/21/2010 - 20:41

Try it with

region no_ins_region intersect 2 ins_cyl ins_cone units box
instead of
region no_ins_region intersect 2 ins_cyl ins_cone side out units box

I think that should do it...

Christoph

strakakl | Fri, 10/22/2010 - 08:11

Hi Christoph,

i tried

region no_ins_region intersect 2 ins_cyl ins_cone units box
instead of
region no_ins_region intersect 2 ins_cyl ins_cone side out units box

but nothing changed. Again the resulting insert region is the cylinder except the cone which is correct because the intersection of the cone and the cylinder is the cone itself. In combination with the pour/def/packing and the regionexcempt keyword this leads to the cylinder except the cone. But i need the cone itself as the insert region, that's why i used the "side out" keyword.

cheers,

Klaus

ckloss's picture

ckloss | Fri, 10/22/2010 - 10:36

You need to do it like that:

region ins_cone cone z 0.04 0.0 0.01 0.065 0.09 0.16 units box side out
region ins_cyl cylinder z 0.04 0.0 0.065 0.08 0.16 units box
region no_ins_region intersect 2 ins_cyl ins_cone side out units box

because the command does intersection, not subtraction. look the "region" manual for details

best,
Christoph

strakakl | Fri, 10/22/2010 - 12:42

hi christoph,

you made my day, it works :) Thanks a lot. But i still wonder about the effect of "side out" in

region no_ins_region intersect 2 ins_cyl ins_cone side out units box

Because running the simulation with eigther

region no_ins_region intersect 2 ins_cyl ins_cone side out units box
or
region no_ins_region intersect 2 ins_cyl ins_cone units box

won't change the insert region.

cu
Klaus

cgrohs | Fri, 10/22/2010 - 17:39

Hello Christoph,

I'm not sure (and had no time to test it) but I think there is a small bug in the fix pour/dev when using regionexempts. My insertion region has a small height and therefore more time steps are necessary to insert all particles. In the first step the insertion region (outer cylinder minus inner cylinder) is correct but in the next dump (when more particles are inserted) some of them are inside the inner cylinder.
I guess a work around for me would be to make the insertion region high enough to insert all particles in the first step (also not tested yet).

Cheers,
Christian

ckloss's picture

ckloss | Sat, 10/23/2010 - 18:37

Hi Christian,

the variant of using pour/dev with "regionexempt" to insert in complex geometry is more a workaround until a better command is available - I am aware that it may fail in some situation

Christoph