Re: [Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-05 Thread Zhicheng Gao
Question #699347 on Yade changed:
https://answers.launchpad.net/yade/+question/699347

Status: Needs information => Solved

Zhicheng Gao confirmed that the question is solved:
> This feature is also what I am researching. In other words, is it best to 
> delete the wall directly and impose periodic boundary conditions?
I am studying the effect of erosion on granular materials.

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Re: [Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-04 Thread Jan Stránský
Question #699347 on Yade changed:
https://answers.launchpad.net/yade/+question/699347

Status: Open => Needs information

Jan Stránský requested more information:
> I want to know if this will have a big impact on the results of the
three-axis experiment?

For sure it will have some impact.
If "big impact", it depends on your definition of what "big" is.

> Can period boundary be used for the anisotropic sample?

yes, definitely.

> This feature is also what I am researching. In other words, is it best
to delete the wall directly and impose periodic boundary conditions?

I am not sure what you mean here, please be more specific (e.g.
"diretly" w.r.t. what?).

Cheers
Jan

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Re: [Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-04 Thread Zhicheng Gao
Question #699347 on Yade changed:
https://answers.launchpad.net/yade/+question/699347

Status: Answered => Open

Zhicheng Gao is still having a problem:
>The problem is that at the "faces" the particles would not match on opposite 
>faces. It would behave like there would be a crack every cell distance.
(The periodicity would work ok, however)

I know what you mean, that is, the particles up and down in the same
direction will not be embedded in the grooves formed by the particles. I
want to know if this will have a big impact on the results of the three-
axis experiment? After the erosion, the particle distribution is not
uniform and it is anisotropic. Can period boundary be used for the
anisotropic sample?

>I meant to create a new periodic packing from scratch. But instead of creating 
>a random packing, you would need to impose the eroded characteristics.
The challenge is how to identify the "characteristics" and then how to impose 
them on the packing.

This feature is also what I am researching. In other words, is it best
to delete the wall directly and impose periodic boundary conditions?

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Re: [Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-04 Thread Jan Stránský
Question #699347 on Yade changed:
https://answers.launchpad.net/yade/+question/699347

Status: Open => Answered

Jan Stránský proposed the following answer:
> Is it possible to directly generate the periodic boundary and then
delete the wall?

It is possible, but it would result in something different than you want.
You can delete walls, you can extract certain area, you can also set periodic 
boundary conditions, it is no problem.
The problem is that at the "faces" the particles would not match on opposite 
faces. It would behave like there would be a crack every cell distance.
(The periodicity would work ok, however)

> The specific process is to save the position and size information of
the particles, then read the information of the particles, and generate
these particles one by one?

This would be too easy :-D
I meant to create a new periodic packing from scratch. But instead of creating 
a random packing, you would need to impose the eroded characteristics.
The challenge is how to identify the "characteristics" and then how to impose 
them on the packing.

Cheers
Jan

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Re: [Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-04 Thread Zhicheng Gao
Question #699347 on Yade changed:
https://answers.launchpad.net/yade/+question/699347

Status: Answered => Open

Zhicheng Gao is still having a problem:
Dear Jan,
Can you provide more information? Thank you.

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Re: [Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-04 Thread Zhicheng Gao
Question #699347 on Yade changed:
https://answers.launchpad.net/yade/+question/699347

Zhicheng Gao posted a new comment:
Dear Jan,
Thank you for your response,  this is my reply and new questions,

> In order to reduce the volume of the representative unit and want to
use periodic boundaries

Yes, I first prepare the sample by isostatic compression in all
directions and then apply a water pressure difference between the upper
and lower interfaces in a certain direction, use PFV to solve it to
simulate the erosion process, and then perform a triaxial test. In order
to be able to perform quantitative analysis, it is necessary to use a
representative unit, but the representative unit with a non-periodic
boundary requires too many particles, so after the erosion, I want to
use the periodic boundary to reduce the number of particles in the
representative unit.

>One option is to create a new periodic sample, preserving characteristics of 
>the original sample. Not straightforward either..
The specific process is to save the position and size information of the 
particles, then read the information of the particles, and generate these 
particles one by one? Is it possible to directly generate the periodic boundary 
and then delete the wall?

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Re: [Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-04 Thread Jan Stránský
Question #699347 on Yade changed:
https://answers.launchpad.net/yade/+question/699347

Status: Open => Answered

Jan Stránský proposed the following answer:
Hello,

in general, it is not straightforward to change non-periodicity =>
periodicity

> In order to reduce the volume of the representative unit and want to
use periodic boundaries,

so you are going to simulate a (much) smaller periodic sample out of
original non-periodic sample?

> how to realize the conversion from non-periodic boundary to the
periodic boundary without disturbing the sample?

One option is to create a new periodic sample, preserving characteristics of 
the original sample.
Not straightforward either..

Cheers
Jan

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[Yade-users] [Question #699347]: How to use periodic boundaries for triaxial test simulation after erosion

2021-11-04 Thread Zhicheng Gao
New question #699347 on Yade:
https://answers.launchpad.net/yade/+question/699347

Since the erosion problem is a boundary value problem, a non-periodic boundary 
is used to simulate erosion, and the confining pressure is applied through six 
walls. After erosion, perform a triaxial experiment. In order to reduce the 
volume of the representative unit and want to use periodic boundaries, how to 
realize the conversion from non-periodic boundary to the periodic boundary 
without disturbing the sample?

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