a cylinder as a single body

Asked by behzad on 2015-02-01

Hi,

I need to create(or import) a cylindrical-shape body and as I see in any case this cylinder is presented by an assembly of facets which means several bodies.

However, what I want to do is measuring the viscosity of a material. It means we apply a moment on a cylinder surrounded by spheres and we measure the shear rate (angular velocity).
So, the problem is how can we treat the cylinder as a single rigid body?

Thanks .

Question information

Language:
English Edit question
Status:
Solved
For:
Yade Edit question
Assignee:
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Solved by:
behzad
Solved:
2015-02-01
Last query:
2015-02-01
Last reply:
2015-02-01
Jan Stránský (honzik) said : #1

Hi Behzad,

you have more options:

1) use O.bodies.appedClumped(facets) to create a clump, which you can aplly
force to. Currently it does not work with facets, but it should not be
difficult to make it work with non-spherical shapes. I don't have time now
to work on it..

2) use normal bodies and use RotationEngine on them, each (or each a few)
time step checking forces on individual facets and apdate angular velocity
according to the value (i.e. creating PyRunner doing the same as
NewtonIntegrator :-)

I like no 1 most (if it works), you can ask some other developers for the
help :-)

cheers
Jan

2015-02-01 20:36 GMT+01:00 behzad <email address hidden>:

> New question #261529 on Yade:
> https://answers.launchpad.net/yade/+question/261529
>
>
> Hi,
>
> I need to create(or import) a cylindrical-shape body and as I see in any
> case this cylinder is presented by an assembly of facets which means
> several bodies.
>
> However, what I want to do is measuring the viscosity of a material. It
> means we apply a moment on a cylinder surrounded by spheres and we measure
> the shear rate (angular velocity).
> So, the problem is how can we treat the cylinder as a single rigid body?
>
> Thanks .
>
> --
> You received this question notification because you are a member of
> yade-users, which is an answer contact for Yade.
>
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> Mailing list: https://launchpad.net/~yade-users
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behzad (behzad-majidi) said : #2

Hey Jan,

Yeah, no.1 seems a good way to work on. The facet bodies, I think must be set as dynamic bodies, though.

Anyway, thanks for the answer. I'll work on it.

cheers,
Behzad

Jan Stránský (honzik) said : #3

I am not sure where the problem is, after appendClumped, the values of
clump.members (i.e. relative position and orientation of clump members are
NaNs..). Setting mass and inertia to facets does not help

Probably nobody needed such feature before, but definitely it may be
considered as a bug, feel free to report it, at least we would not forget
to fix it :-)

cheers
Jan

2015-02-01 22:26 GMT+01:00 behzad <email address hidden>:

> Question #261529 on Yade changed:
> https://answers.launchpad.net/yade/+question/261529
>
> Status: Answered => Solved
>
> behzad confirmed that the question is solved:
> Hey Jan,
>
> Yeah, no.1 seems a good way to work on. The facet bodies, I think must
> be set as dynamic bodies, though.
>
> Anyway, thanks for the answer. I'll work on it.
>
> cheers,
> Behzad
>
> --
> You received this question notification because you are a member of
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behzad (behzad-majidi) said : #4

How can I find appendClumped function to modify it?

Jan Stránský (honzik) said : #5

pyBodyContainer::appendClump
http://bazaar.launchpad.net/~yade-pkg/yade/git-trunk/view/head:/py/wrapper/yadeWrapper.cpp#L135
calling pyBodyContainer::clump
http://bazaar.launchpad.net/~yade-pkg/yade/git-trunk/view/head:/py/wrapper/yadeWrapper.cpp#L116
calling Clump::add and Clump::updateProperties (see core/Clump.*pp). I
guess the problem is in the Clump methods..

Jan

2015-02-01 23:16 GMT+01:00 behzad <email address hidden>:

> Question #261529 on Yade changed:
> https://answers.launchpad.net/yade/+question/261529
>
> behzad posted a new comment:
> How can I find appendClumped function to modify it?
>
> --
> You received this question notification because you are a member of
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Christian Jakob (jakob-ifgt) said : #6

Hi,

updateProperties function assumes, that clump members are spheres. it will not work for facets atm ...

regards,

christian

Jan Stránský (honzik) said : #7

@Christian: Ok, I see.. the correction for non-spherical particles should
not be too difficult

@Behzad: how much is it urgent for you?

Jan

2015-02-02 7:31 GMT+01:00 Christian Jakob <
<email address hidden>>:

> Question #261529 on Yade changed:
> https://answers.launchpad.net/yade/+question/261529
>
> Christian Jakob posted a new comment:
> Hi,
>
> updateProperties function assumes, that clump members are spheres. it
> will not work for facets atm ...
>
> regards,
>
> christian
>
> --
> You received this question notification because you are a member of
> yade-users, which is an answer contact for Yade.
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behzad (behzad-majidi) said : #8

I need to have the modifications(or another way to deal with this problem) in two weeks.

Jan Stránský (honzik) said : #9

Ok, I will have a look during the weekend, is it ok?
Jan

2015-02-02 16:21 GMT+01:00 behzad <email address hidden>:

> Question #261529 on Yade changed:
> https://answers.launchpad.net/yade/+question/261529
>
> behzad posted a new comment:
>
> I need to have the modifications(or another way to deal with this problem)
> in two weeks.
>
> --
> You received this question notification because you are a member of
> yade-users, which is an answer contact for Yade.
>
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behzad (behzad-majidi) said : #10

Sure! Thanks.

Jan Stránský (honzik) said : #11

Hi Behzad,
the non-spherical clumps should be possible to use in latest trunk version
(r3576). I added an example, in principle doing exactly what you want,
yade/examples/test/clump-facet.py
cheers
Jan

2015-02-04 17:06 GMT+01:00 behzad <email address hidden>:

> Question #261529 on Yade changed:
> https://answers.launchpad.net/yade/+question/261529
>
> behzad posted a new comment:
> Sure! Thanks.
>
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behzad (behzad-majidi) said : #12

Hi Jan,

yes, I tried it and it does what I wanted. Thank you!

cheers,
Behzad

behzad (behzad-majidi) said : #13

Hey Jan,

Can I share some files with you?
I'm importing two bodies as stl files in YADE and I define them as clumps. They're having unrealistic interactions.

Jan Stránský (honzik) said : #14

Hi Behzad,
sure, you can also (preferably) place the files somewhere on the web such
that others can download them and help, too.
cheers
Jan

2015-02-10 20:36 GMT+01:00 behzad <email address hidden>:

> Question #261529 on Yade changed:
> https://answers.launchpad.net/yade/+question/261529
>
> behzad posted a new comment:
> Hey Jan,
>
> Can I share some files with you?
> I'm importing two bodies as stl files in YADE and I define them as clumps.
> They're having unrealistic interactions.
>
> --
> You received this question notification because you are a member of
> yade-users, which is an answer contact for Yade.
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behzad (behzad-majidi) said : #15

Thanks the problem is solved.

Cheers