I hoped the "actually" would convey the "positive energy" meaning (like I would 
speak of a "true" acceleration for an increasing speed), but it seems it's not 
the case...


I still prefer "my" proposal but I would not oppose any further changes !



--------------------------------------------------

Jerome Duriez, Research Associate

University of Calgary, Dpt of Civil Engineering

+1 403 220 7367


________________________________
From: Yade-dev <yade-dev-bounces+jerome.duriez=ucalgary...@lists.launchpad.net> 
on behalf of Bruno Chareyre <bruno.chare...@grenoble-inp.fr>
Sent: July-28-16 11:06 AM
To: yade-dev@lists.launchpad.net
Subject: Re: [Yade-dev] TriaxialStressController.externalWork sign

XLatexIt! run report...

*** Found expression $u$
*** Found expression $T$
*** Found expression $ \int_{\partial \Omega} \boldmath T \cdot  \bm u ds$
Image was already generated



I don't think it makes much sense to speak of whether it is negative or 
positive.


"negativ when the boundaries actually provide energy to the sample", you mean 
when the boundaries actually provide a positive energy to the sample?

Since if it provides a negative energy then the function will return a positive 
value. ;)

I would suggest plain mathematical definition:

"Mechanical work associated to the boundary conditions, i.e. [$               
\int_{\partial \Omega} \boldmath T \cdot  \bm u ds$]  with [$T$]  the surface 
traction and [$u$]  the displacement at the boundary."


There is no strong argument to multiply such a straight definition by -1 in my 
view.


Bruno



On 07/28/2016 06:33 PM, Jerome Duriez wrote:

Ok, I just proposed something:

https://github.com/yade/trunk/commit/6a9b6178ebade3c6d5ea6cbcdf439a9f20073648

[https://avatars1.githubusercontent.com/u/5427081?v=3&s=200]<https://github.com/yade/trunk/commit/6a9b6178ebade3c6d5ea6cbcdf439a9f20073648>

Doc clarification for TriaxialStressController.externalWork (http://w… · 
yade/trunk@6a9b617<https://github.com/yade/trunk/commit/6a9b6178ebade3c6d5ea6cbcdf439a9f20073648>
github.com
…ww.mail-archive.com/yade-dev@lists.launchpad.net/msg12083.html<mailto:ww.mail-archive.com/yade-dev@lists.launchpad.net/msg12083.html>)




Thanks,


Jerome



--------------------------------------------------

Jerome Duriez, Research Associate

University of Calgary, Dpt of Civil Engineering

+1 403 220 7367


________________________________
From: Yade-dev 
<yade-dev-bounces+jerome.duriez=ucalgary...@lists.launchpad.net><mailto:yade-dev-bounces+jerome.duriez=ucalgary...@lists.launchpad.net>
 on behalf of Bruno Chareyre 
<bruno.chare...@grenoble-inp.fr><mailto:bruno.chare...@grenoble-inp.fr>
Sent: July-28-16 10:06 AM
To: yade-dev@lists.launchpad.net<mailto:yade-dev@lists.launchpad.net>
Subject: Re: [Yade-dev] TriaxialStressController.externalWork sign


Hi Jérôme,

Strictly speaking the doc is right: "Energy provided by boundaries" does not 
tell if the boundaries provide energy to the sample or to the outside.

I agree that it is probably more common to define "external work input" as an 
input to the sample, yet overall it remains a matter of taste.

I'm not for discussing/changing such sign conventions unless they are obviously 
wrong. There are probably tons of user scripts which would have to be adapted 
after such change (including mines), not a good thing. Instead, I would clarify 
the documentation without changing the code.

Bruno

On 07/27/2016 07:26 PM, Jerome Duriez wrote:

Hello,


I'm proposing to change the sign convention of 
TriaxialStressController.externalWork.


I would like it corresponds to the "Energy provided by boundaries" as the doc 
says, however it seems to me it's currently rather the energy provided to the 
boundaries (by the sample). Since we use the Force acting on the boundaries 
together with the boundaries velocities.


Agree to revert this sign ?


Jerome



--------------------------------------------------

Jerome Duriez, Research Associate

University of Calgary, Dpt of Civil Engineering

+1 403 220 7367



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