Error - dump file requires all parameters from a compute pair/gran/local id pos force (11 in total)

Submitted by DAVID RIVERA TAPIA on Wed, 07/11/2012 - 16:52

Hi, everybody

When i'm trying to get the force chain in a particle assembly using dump2force.py dump.fc.1000.liggghts i got thir error:

Error - dump file requires all parameters from a compute pair/gran/local id pos force (11 in total)

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ckloss's picture

ckloss | Thu, 07/12/2012 - 15:09

>>Error - dump file requires all parameters from a compute pair/gran/local id pos force (11 in total)
I guess that is pretty self-explanatory? What compute pair/gran/local command did you use?

EDIT: moved this topic to the post-processing section

Christoph

msbentley's picture

msbentley | Fri, 07/13/2012 - 10:29

The error message should in fact say 12 values, not 11. Your compute calculates:

id = IDs of particles in contact and a periodicity flag (3 values) or IDs of the mesh, the triangle and the particle (3 values)
pos = positions of particles in contact (6 values)
force = contact force (3 values)

So this compute calculates 12 values, and you need to dump all 12 to a file.

Cheers, Mark

msbentley's picture

msbentley | Fri, 07/13/2012 - 10:22

Hi there,

Yes, I'm afraid the code simply assumes a default set of dump local data - you can modify as you need to include additional output. By default I think dump2force assumes you are doing something like

compute fc all pair/gran/local id pos force
dump forcedump all local 100 dump.forcedata c_fc[1] c_fc[2] c_fc[3] etc. up to c_fc[12]

which produces 12 outputs:

x1 y1 z1 x2 y2 z2 id1 id2 periodic fx fy fz

You can find some lines in the code to also write out contact area and heat flux to VTK files if you've included those in your dump local - you just have to uncomment them.

So you should either modify dump2force to exclude data you don't want, or dump the data listed above. Hope that helps!

Cheers, Mark

mhk | Tue, 08/20/2013 - 03:47

I was wondering if the order of 12 components in output for compute wall/gran/local is similar to pair/gran/local. I have used both commands (compute pair and wall), but the output of compute wall/gran/local is as follows:
x1 y1 z1 x2 y2 z2 PERIODIC id1 id2 fx fy fz
another question, what is "periodic"?