fix pour query

Hello everyone,

I am a undergrad student and I am currently working on segregation models. I wanted to ask a question about fix pour :
We know that the syntax is :
fix ID group-ID pour N type seed keyword values ...

However, if we are using two diameters like :

fix 2 all pour 10000 1 19985583 region disk diam poly 2 0.7 0.4 1.5 0.6

Is there a way to assign a different atom type to each diameter? I know it won’t make any difference in the simulation. But it would definitely be easy to visualize in vmd. If not, what alternative can be used?

Thanks,

Sonu Kumar

3rd Year, B’Tech in Chemical Engineering

IIT Guwahati

Thanks for clarifying that this is a visualization question. I’m not a user of vmd, but in programs like tecplot (popular in the computational fluid dynamics community) you can easily color or filter by some variable, diameter here. Its probably not a feature unique to tecplot.

It’s a bit clunky, but the molecule command will let you read a series
of files and assign a atom-type offset to each one. And a different
scale factor (diameter in your case) for each one. So you could
create a molecule file with a single atom in it. Then read it M
times with the molecule command and give each instance a different type offset
and diameter.

Then use the fix pour command with the mol and molfrac keywords
to insert those molecules the same as you are now with the diam and
poly keywords. Each diameter particle (molecule) will be a different type.

Never tried it, but I think it should work.

Steve

Hello everyone,

I am a undergrad student and I am currently working on segregation models. I
wanted to ask a question about fix pour :
We know that the syntax is :
fix ID group-ID pour N type seed keyword values ...

However, if we are using two diameters like :

fix 2 all pour 10000 1 19985583 region disk diam poly 2 0.7 0.4 1.5 0.6

Is there a way to assign a different atom type to each diameter? I know it
won't make any difference in the simulation. But it would definitely be easy
to visualize in vmd. If not, what alternative can be used?

this can be easily rectified from within VMD for as long as you
include the diameter information in your dump file.
within VMD you can combine multiple representations with different
colors or other properties and use the VMD selection language to
select which radius (n.b. diameter is converted to radius when reading
dump files) of atoms each representation applies, you can even match
ranges with > or < comparisons.
if you absolutely want to have numerical atom types applies, to
particles with different radius/diameter, this can be done with
scripting on the console as well.

axel.