Using different partial sizes Beginner please help?

Submitted by aquinolarosa on Mon, 02/29/2016 - 02:31

I am a beginner and trying to figure my way around liggghts. I am using 3x materials (1x big particle, 1xsmall particle, 1xbin). As the particles are of difference sizes which command do I use to define the different particle sizes and how would this affect the neighbour lists.

thanks in advance for your help.

Forums:

aaigner's picture

aaigner | Wed, 03/02/2016 - 17:33

Hello aquinolarosa,

first question: 3 materials or the same material with different particle diameter?

Let's asume the latter, thus we have one material (with two radii) and one material for the bin. (in total 2)
We start from an example like the chute_wear example in your LIGGGHTS-PUBLIC/examples/LIGGGHTS/Tutorials_public/chute_wear directory. By default this example has only 1 type (particle = wall).
You have to change:

  • create_box ... 1 -> 2
  • all property/global where
    • peratomtype gets a second value
    • peratomtypepair changes 1 -> 2 and it needs a 2x2 matrix ... 4 values
  • finally you have the two particletemplate/sphere with the same material but different diameter (type 1)
  • and the mesh/surface command should change the type from 1 -> 2

The particle distribution is defined in the same-named command ...

Well.. the neighbour list uses the smallest particle diameter by default, but you can ajust the binsize via the neigh_modify command.

Bests
Andreas