control the porosity

Asked by fengjingyu on 2018-12-16

Hi,

I'm reproducing a paper on isotropic compression.My material is exactly the same as the numerical value in the paper.However, to speed up the simulation, I used 1/100th of his particles and magnified them 100 times. I ended up 30 percent less porosity than he was. Does adjusting the number and size of particles really have that much effect on porosity? How should I adjust it at this time?

Thanks,

Feng

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Last query:
2018-12-16
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2019-01-02
Jan Stránský (honzik) said : #1

Hi Feng,

please be more informative. There are too many unknowns..

> I'm reproducing a paper on isotropic compression

never hurts to mention which one :-) actually it might be very important

> My material is exactly the same as the numerical value in the paper.

Is also the constitutive law the same? Damping? Time step? Loading and stop conditions? ....
Material itself is necessary but definitely not at all sufficient condition to get the same results..
What software is used in the paper?

> I used 1/100th of his particles and magnified them 100 times

what was the original number of particles? 1000? 1,000,000?

> I ended up 30 percent less porosity than he was. Does adjusting the number and size of particles really have that much effect on porosity?

maybe yes and maybe no :-) for relevant comparison, it would be good to use your method and reproduce the original number of particles and compare it to the reduced problem. Maybe your simulation with original number of particles also differs 30% from the paper and the difference lies somewhere else than number of particles..

cheers
Jan

fengjingyu (fengjing) said : #2

Hi Jan,

You've already seen my other question(https://answers.launchpad.net/yade/+question/676841).I think my porosity is different from the paper probably because the porosity function that comes with yade doesn't take into account particle overlap.I will use voxelPorosity try again.

Besides,the paper i am reading is <Numerical study of one-dimensional compression in granular materials>.

Thanks,
Feng

Jan Stránský (honzik) said : #3

Just a note, pomputing porosity "by hand" taking into account real overlap is not difficult and IMO would be much faster and much more precise than voxelPorosity, but it is up to you.
Jan

fengjingyu (fengjing) said : #4

Hi Jan,

Thanks your remind.But as a beginner, I don't know what imo is. I didn't find it on the Internet. Could you be more specific? Thank you.

Feng

Jan Stránský (honzik) said : #5

IMO = in my opinion

Launchpad Janitor (janitor) said : #6

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