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[Chiara Modenese <c.modenese@xxxxxxxxx>]

I think that Giuseppe may have a point. One problem with shearing the 
periodic cell by rotating it is that you can reach very large 
deformations but at some point (I suppose) you have to stop shearing it 
(because, say, you reach a rotation of 90 degrees of the vertical 
boundaries). Now, one alternative could be:
1) to maintain a full 3d periodic boundary condition
2) to adjust the top boundary if under stress-controlled conditions
3) to prescribe a simple shear by applying the velocity gradient but 
without affecting the vertical boundaries (so only particles would be 
influenced by that but the lateral boundaries would stay vertical).
In principle this would allow for a continuous shear flow. Bruno, do you 
think it would work? It is more question if that makes sense other than 
how actually doing it.

Chiara


On 01/02/2012 17:41, Chareyre wrote:
> Question #186515 on Yade changed:
> https://answers.launchpad.net/yade/+question/186515
>
>      Status: Open =>  Answered
>
> Chareyre proposed the following answer:
> Hi Giuseppe,
>
> First, make sure you read https://www.yade-dem.org/doc/formulation.html
> #deformations-handling carefuly. You will see that you are not supposed
> to change cell.trsf (and that is why you can't change it).
>
> Second, I don't understand what "prevent shear" means. Or more
> precisely, I don't understand why your simulation results in a shear if
> you don't prescribe one yourself (well, if you run a simple shear test
> you have to prescribe a shear I guess, but then why would you prevent
> while imposing?... I'm lost).
>
> Bruno