Wishlist: make it more explicit in the doc (maybe even return a warning
when changing angular velocity of aspherical objects).
** Changed in: yade
Status: New => Opinion
** Changed in: yade
Importance: Undecided => Wishlist
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https://bugs.launchpad.net/bugs/1595450
Title:
Cannot apply an angular velocity to aspherical objets
Status in Yade:
Opinion
Bug description:
Yade versions : all
I am surprised to see that we can't apply an angular velocity to
aspherical objects like clumps. If we set angVel at time T, the
modification is overwritten at time T+DT, ignoring the entered value
(see attached script).
It is due to the rotation implementation for asphercial bodies, and a comment
is present here in the code :
https://github.com/yade/trunk/blob/master/pkg/dem/NewtonIntegrator.cpp#L242
It is not possible to workaround with aspherical body attribute, as passing
an object from aspherical=False to aspherical=True resets all its state vectors
to (0.,0.,0.).
If no algorithm is available to perform this, it would be nice to
alert the user that the angVel he has just set is not taken into
account.
But the most disturbing element is here, in the clump tests :
https://github.com/yade/trunk/blob/master/py/tests/clump.py#L56
1°) we set the clump translational and angular velocity
2°) we make one timestep
3°) we check the clump elements positions and velocities (angular and
translational) according to the (updated, so mistakenly set to zero) values of
angVel. Thus, these values do not correspond to the ones set in 1°) as they
were overridden, and the test succeeds, with no real check of the angVel
functionality.
Thanks to Gonzalo Cruz-Alcala and David Toe for the script and the bug
reporting.
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