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Re: DEM equations, written down.


kan said:     (by the date of Fri, 2 Oct 2009 17:49:18 -0500)

> Hi,Mr. Janek,
> I have some questions;
> 1. for equation (34), I think the mi should not be there, what do you think?

that's a simplifications on yade's side. Go into code and see how `I`
is calculated. You will see that `I` is already multiplied by mass, to
save on repeating this one multiplication every time . I was against
this from start, but Olivier insisted that optimisation is so
important... I would prefer to either rename `inertia` to
`inertia_times_mass` or removing mass from it.

> 2. for the contact moment M(vector), in eqn (25), what is the physical
> meaning?

it's as if the spheres were glued together. Or as if they had a rough
surface which is able to transfer moment. If you use contact moments
and have a "line" of spheres touching each other, then they behave as
a one long beam.

Janek Kozicki                                                         |

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