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[Vincent Richefeu <richefeu@xxxxxxxxxxxxxxx>]

This is exactly what JJ Moreau did (so I think one can have some confidence with that) for spheres into a spherical probe (subvolume).
Since the intersected volume can be analytically computed, he summed the moment tensor of each sphere weighted by the ratio "insidePartVolume" / "sphereVolume", and divided this sum by the probe volume. I think Vaclav solution (i.e. with weighted branch vectors) is equivalent (it could be proved by replacing the branch vector by 2 "radius vectors" and taking into account the reciprocal actions of contact forces).

Vincent

Le 9 févr. 2011 à 15:11, Václav Šmilauer a écrit :

> If the subvolume is a box (or parallelepiped in general), you could weight the contribution rather easily by length of the interaction that is inside that volume; i.e. interactions fully inside would have w=1, one that would be 1/3 of its length inside would have w=1/3 and such. If you want to compute the stress tensor in multiple adjacent subvolumes at the same time, it would be quite efficient, i.e. splitting the periodic cell in a regular grid of subvolumes, then just finding which subvolume it belongs to.
> 
> Hope I understood what you are after.
> 
> v.
> 
> 
>> 
>> 
>> 
>> Method2 (easier) : define a group of spheres and compute weighted average stress using per-body stresses (bodyStressTensors in utils). You'll have to define the total volume of the subdomain though, which is a bit more tricky than with method 1. 
>> I think that defining the subvolume will not be a problem. But what happens if the branch vector of the interaction crosses the subdomain? Can this be an issues?
>> Chiara
>>  
>> 
>> Cheers.
>> 
>> Bruno
>> 
>> 
>>  
>> 
>> On 09/02/11 12:03, Chiara Modenese wrote:
>>> Hi,
>>> I would like to compute the average stress tensor into subdomains of periodic cell. Any hint how to do that and where to add it (is Shop the best place?)?
>>> Thanks, Chiara
>>> 
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