pair/gran/local visualization and Hollow spheres

Submitted by stephane.griffiths on Thu, 09/06/2012 - 15:23

Dear LIGGGHTS Community,

I was just wondering if someone could explain me how to visualize or use the data calculated by the pair/gran/local function defined as :

compute forces all pair/gran/local id pos force
dump forcedump all local 400 post/dump.force c_forces[1] c_forces[2] ... c_forces[12]

I can convert a dump.file from dump/custom to vtk using the lpp function, but in that case (dump/local), it doesn't work. I saw that the generated files does not look the same at all. But if someone has a tip or an advice to help me visualizing the results from dump/local with ParaView, that would be nice.

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Also, I had an other question. I'm currently working with atom_style/granular. In the model I'm working on, I have to use hollow beads. Do you know if there is a way for me to change the files and try to convert the solid spheres to hollow sphere ?
Maybe changing particleToInsert.cpp/.h adding an internal radius in order to create an cavity in the sphere ? Also a gas has to be present in the cavity.
If someone has an idea on how to do that, that will be really helpfull.

Thanks a lot for your help and your patience.

Stéphane

Forums:

ckloss's picture

ckloss | Sun, 09/16/2012 - 23:47

Hi Stéphane,

Mark Bentley (user/649) wrote a very nice tool to do that, but I couldn't catch up and fully integrate into the official lpp yet.

Regarding the hollow sphere question: I would simply add the density of the sphere on the DEM side. Modelling the gas inside the sphere seems like a job for an immersed boundary / fictitious domain method - we have this in CFDEMcoupling, but it would require some adaptions to do exactly what you want

Cheers, Christoph

stephane.griffiths | Tue, 09/18/2012 - 15:11

Hi Christoph,

Thanks a lot for your answer. In order to read the dump/local file, I just wrote a few matlab lines.

Regarding the hollow spheres, I already used the density of the sphere on the DEM side. I was thinking that maybe I could create "real" hollow beads using the equation of motion of the system "bead-gas inside the bead". But I could'nt figure out how were created the spheres.

Just one last question Christoph: Do you know if I can create a mesh pushing an other mesh ? Maybe using a spring between the two meshes.

Thanks a lot for your help and for everything you and the LIGGGHT team are doing !!

Best,
Stephane

ckloss's picture

ckloss | Wed, 09/19/2012 - 17:12

Hi Stephane
>>Do you know if I can create a mesh pushing an other mesh ?
that's not possible at the moment. however, it would be possible to e.g. create a new "primitive" wall as a hollow sphere, use 2 of them and connect them in a fix spring-like fashion

>>Thanks a lot for your help and for everything you and the LIGGGHT team are doing !!
thanks - you're welcome!

Christoph