yade-users team mailing list archive

[nejib hadda <nejib.hadda@xxxxxxxxxxx>]

Hi,

I find this totally obvious since you assign values of ids yourself.

Ids on Yade are assigned for evry body since the creation of your
specimen: walls(id = 0-->nbr_walls-1) and spheres
(id=nbr_walls-->nbr_bodies-1).

When two bodies come into contact you can display their ids as follow
(python):

import pylab 
import numpy
ofile = open('contactforces','w')
ofile.write("id1 id2 nx ny nz fx fy fz FORCE \n")
axis=0 # (plot the yz plane)
x,y,z=(axis)%3,(axis+1)%3,(axis+2)%3 
forces=[]

CompFn=0

Fnx,Fny,Fnz=(CompFn)%3,(CompFn+1)%3,(CompFn+2)%3

for j in O.interactions:
	if not j.isReal: continue
	norm=j.geom['normal']
	FORCE=j.phys['normalForce'].Length()
	force=j.phys['normalForce']
	index1=j.id1
	index2=j.id2
	#angles.append(angle)
	#forces.append(force)
	if index1>5 and index2>5 :  ### Only sphere-sphere contact###
		angle_yz=atan2(norm[z],norm[y])
		angle_xz=atan2(norm[z],norm[x])
		angle_xy=atan2(norm[y],norm[x])
		ofile.write('%g %g %g %g %g %g %g %g %g %g %g %g\n' %
(index1,index2,norm[x],norm[y],norm[z],force[Fnx],force[Fny],force[Fnz],FORCE))
	
ofile.close()



and of course this can tell the  interactions at evry iteration!



Le mercredi 24 mars 2010 à 12:51 +0000, chiara modenese a écrit :
> Hi all,
> 
> quick question on the ids of two bodies in contact. I took an example
> where a box and a sphere get in contact. Then I simply switched the id
> of the two and I checked the ids of the interaction. To put it better
> I obtained:
> 
> 1) case 
> 
> box -> id=0
> sphere -> id=1
> 
> Interaction:
> id1=0 (box)
> id2=1 (sphere)
> 
> 2) case (I switch ids, alias I change the sequence in which I append
> the two bodies)
> 
> sphere -> id=0
> box -> id=1
> 
> Interaction:
> id1=1 (box) ---> why it is not id=0 as in the first case?
> id2=0 (sphere)
> 
> My question is: how are assigned the ids of the contact once the
> interaction is created? 
> Just to know..
> 
> cheers, Chiara
> 
> 
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