generate two different radius particle in a box

Hi,

this question has been asked a couple of times. Check out those topics [1,2]

Best wishes,
Karol

[1] https://answers.launchpad.net/yade/+question/647318
[2] https://answers.launchpad.net/yade/+question/695989

Hi,Karol

The information you provided is useful to me, but i am still have some questions. If i can use the method randomDensePack to replace the method makeCloud use in the topics [1,2] you gave to me? Because I want to generate particles of small size to fill the pores of dense particles of large size, but i don't know how to achieve it by method randomDensePack.

[1] https://answers.launchpad.net/yade/+question/647318
[2] https://answers.launchpad.net/yade/+question/695989

Hi,

I don't think that you can do this with randomDensePack (I am not sure though). I think that the simplest approach would be to:
- generate packing with makeCloud() inside a bigger cube,
- generate six walls around the packing and compress the packing until some condition is reached (stress or porosity, etc.)
- export your packing to an external file.

If you need a more specific answer, you should share more details [1]. Especially, after you try to implement some solution by yourself.

Cheers,
Karol

[1] https://www.yade-dem.org/wiki/Howtoask

Hello,

No, you cannot use randomDensePack to do this. But you can very easily replicate randomDensePack action by increasing particle radii yourself according to the stresses on the walls.

Add a pyrunner to your engines list:

PyRunner(command='addStress()',dead=1,iterPeriod=10,label='loadSample')

Then add the following function to your script:

## Set mn,mx. They should be the values you used to create the aabbWalls. 'walls' should be a list of the ids of your walls.
multiplier = 1.001

def addStress():
        global multiplier
        preStress = 5e3
 maxMultiplier=1.001
 growParticles(multiplier)
 pressure = 0

 for i in walls:
  f = O.bodies[i]
  a = mn[0]*mn[1]
  force = O.forces.f(f.id,sync=True)
  pressure = pressure + np.linalg.norm(force)/a

 stabCoeff = abs((abs(pressure/len(walls))-preStress)/preStress)
 facetStress = abs(pressure/len(walls))
 print('unbalanced force:',unbalancedForce(),'avg top pressure ',facetStress ,'stability coeff ',stabCoeff)
 multiplier = 1+(preStress-facetStress)/preStress * (maxMultiplier-1.)
 if multiplier <= 0.95: multiplier=0.95
 print('multiplier adjusted up to ', multiplier)

        if stabCoeff<0.001:
            print('packing finished, export it to file ;)')
            loadSample.dead = 1
            O.pause()

I hope it is obvious that this should not be active during any scientific simulation, this is just to achieve a dense packing. Best practice would be to export this packing to file using export.textExt() and then import that packing into whatever you need to do. I leave the export/import up to you as homework ;).

Cheers,

Robert

Hello,

> I've just started using yade recently

welcome :-)

you can try something like (not tested):
###
sp = pack.randomDensePack(...,returnSpherePack=True) # big particles
sp.makeCloud(...) # small particles
sp.toSimulation()
###

Cheers
Jan