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Re: [Question #689234]: How to export relative velocity of spheres to Paraview


Question #689234 on Yade changed:

    Status: Open => Answered

Jan Stránský proposed the following answer:
> Can I get the formula for relative velocity [1] somewhere in Yade? Or
I have to define one by myself?

AFAIK you have to write it yourself..

you can write a function to it and call the function in exportInteractions / exportContactPoints, but as the commands are evaluated only locally, you have to "make the function global", e.g. using __builtin__ module (be very careful with this workaround not to overwrite some python basics, e.g. list etc.):
def relativeVelocity(interaction):
   i1,i2 = interaction.id1, interaction.id2
   b1,b2 = [O.bodies[i] for i in (i1,i2)]
   r1,r2 = [b.shape.radius for b in (b1,b2)]
   v1,v2 = [b.state.vel for b in (b1,b2)]
   ... # actual code comes here
   return relativeVelocity

import __builtin__ # or buitlins (2ithout underscores) in Python3
__builtin__.relativeVelocity = relativeVelocity

vtk.exportInteractions(what=..."relativeVelocity(i)"...) # now you can use relativeVelocity inside exportInteractions


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