yade-users team mailing list archive

["Luc SIBILLE" <Luc.Sibille@xxxxxxxxxxxxxx>]

> Hello,
>
> In the script file
>
> https://yade-dem.org/index.php/ScriptPlotInteractionForcesHistogram
>
> I don't understand why the interaction forces are shown only in the
> range [-90, 90] whereas the componnents of the contact's normal ny and
> nz ranges both in [-1, 1].
> I think that the force interactions belonging to the side [90, 270] are
> superposed with these belonging to [-90, 90] (because the division of
> nz/ny which gives a positive value when nz and ny are both negative for
> example).
>
> Actually we expect some symmetry in such presentation but it still
> confusing.

I don't know the script ScriptPlotInteractionForcesHistogram, but your
right there is a symmetry because contacts are characterized by a
direction but not a sense: for instance contacts with a direction equal to
10 deg are equivalent to contacts with a direction 10+180=190 deg
>
> In addition, for my study case I displayed the interaction forces
> histogram and I found that I have an important interaction forces
> concentration near the angles 0, 90 and -90. Can somebody tell what is
> the problem ??

Your problem may be the following one:
For perfectly smooth walls,  sphere-wall contacts are normal to the walls,
that can lead to a more important number of contacts in directions 0, 90,
180 and 270 deg. To avoid this problem, you need to discard sphere-wall
contacts when you plot contact direction histograms.

Best Luc

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