Yade

How to delete 10% percent of small particles?

Asked by zheng

Dear all,

I am very new in Yade. In my simulation, I have a polydisperse particle size distribution, from size 0.2~1.0mm. Thanks to this poster: https://answers.launchpad.net/yade/+question/211937, I now know how to delete all particles with a certain diameter or position.

Now I need to delete 10% of the smallest particles (d=0.2mm) every 100 steps, but I cannot figure out how to realize this function? Could anyone please give me any clues? Thanks so much!

Best regards,
Zheng

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Solved by:
Robert Caulk
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Best Robert Caulk (rcaulk) said : 		#1

I guess it's a python question.

import numpy as np

def delBelowPercentile(a, q):
    maxRad = np.percentile(a,q)
    for b in bodyRadius:
       if b[0].shape.radius <= maxRad:
           O.bodies.erase(b[0].id)

bodyRadius = []
for b in O.bodies:
    if isinstance(b.shape,Sphere):
        bodyRadius.append([b,b.shape.radius])

bodyRadius.sort(key=lambda x: x[1])
delBelowPercentile(bodyRadius,10)

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Jan Stránský (honzik) said : 		#2

Hello,

use PyRunner [1]:
###
def getSmallParticles():
   ret = []
   # fill ret with particles satisfying "10% percent of small particles"
   return ret

def deleteSmallParticles():
   for b in getSmallParticles():
      O.bodies.erase(b.id)

O.engines = [
   ...
   PyRunner(iterPeriod=100,command="deleteSmallParticles()"),
]
###

cheers
Jan

[1] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.PyRunner

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zheng (tigerhz) said : 		#3

Thanks Caulk and Jan, this solved most of my question. However, deleting particles by sizes may not be suitable for all cases. For example, how to delete 10% of particles by number if I only have one particle size? This time the "percentile(a,q)” may not work. Could you please give me any clues? Thanks so much.

Best regards,
Zheng

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Robert Caulk (rcaulk) said : 		#4

Why don't you give that a shot and tell us where the difficulties lie?

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zheng (tigerhz) said : 		#5

Thanks Robert Caulk, that solved my question.