yade-users team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

On 18 March 2010 18:38, Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx> wrote:

>
>   what about the shear velocity? Do you agree that the way we define it is
>> related to a local system? This is simple to see, just try to invert the ids
>> and you will see what I mean.
>>
>
> No! It is not related to any local system!
> Let grainA with id=1, grainB with id=2.
>
> Compute relVel, then force=f is applied by grainA on grainB.
>
> Now let grainA with id=2, grainB with id=1.
>
> the force is now -f, but it represents the one applied by grainB on grainA.
> What's wrong? This holds whatever the convention.
>
> Now, going from one convention to the other just results in 2 sign
> inversions, you get force=-f instead of force=f, but you apply "force" on
> body1 instead of body2. Same result.
>
> Ops, I was not considering the last sign conversion... Now I see! Thanks a
lot ;)
Chiara


> B.
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