yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

Hi Chiara,

I'm sending the result (after 10min, I could't find the script, sorry).
Looking at your script, I think there is a small mistake in terms you 
define : external work should be compared to 
total=elastic+kinetic+dissipated.
Your script is including external work in total energy, it cannot show 
conservation.
You'll see that I initialized total energy at 0 at the begining of 
compression. Said otherwise, I only plot the _variation_ of internal 
energy, and it matches very well the external input energy from boundaries.

Cheers.

Bruno


On 19/07/10 11:49, chiara modenese wrote:
> Hi all (Bruno?),
>
>
> I spent a bit of time on energy considerations. I remember Bruno 
> saying that in the TT energy is conserved (could you post the example 
> you tried, please?). I post a simple script which plots energy terms 
> and total energy as well. I also post the graph I obtained (your 
> output if you run the script). I am using default parameters, and NO 
> damping at all. The total energy seems to increase in the triaxial 
> phase. Why?
> I checked in the code the way we calculate the external work done by 
> the walls and it looks correct. Look at the unbalanced force in the 
> graph. My conclusion is that as long as the system is dynamic, energy 
> appears to be not conserved. If I am not wrong, this could be a 
> problem for people running simulation in a dynamic state rather than 
> in quasi-static equilibrium. Still unclear why to me.
>
>
> If you have a bit of time just have a look, the script could not be 
> simpler.
>
>
> Cheers. Chiara
>
>
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--
_______________
Bruno Chareyre
Associate Professor
ENSE³ - Grenoble INP
Lab. 3SR
BP 53 - 38041, Grenoble cedex 9 - France
Tél : +33 4 56 52 86 21
Fax : +33 4 76 82 70 43
________________

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