yade-users team mailing list archive

[Vasileios Angelidakis <question690618@xxxxxxxxxxxxxxxxxxxxx>]

Question #690618 on Yade changed:
https://answers.launchpad.net/yade/+question/690618

    Status: Open => Answered

Vasileios Angelidakis proposed the following answer:
Hi Jie,

> If the Axis-Aligned Bounding Box is not accurately defined in
Potential Blocks, what effect will it have on contact?

If you use an approximate Aabb which is smaller than the actual
particle, you will not detect contacts that should be detected, allowing
large overlaps, and if it is much larger, it will make your simulation
slower, without any gains.

The Aabb of a Potential Block is calculated automatically when
PotentialBlock.AabbMinMax=True. It is in the Potential Particles code
that you have to define it manually for the time being.

The parameters minAabb, maxAabb are only used by the
PotentialBlockVTKRecorder to visualise the particles. These parameters
can be assumed to be the same when the particle is more or less
symmetric. Also, as a fail-safe, when the user does not assign values
for minAabb, maxAabb, the PotentialBlockVTKRecorder considers the actual
Aabb of the particles, enlarged by 20%. The minAabb, maxAabb parameters
are not defining the actual Aabb used for contact detection; they are
used only for visualisation purposes in VTK, for the PotentialBlocks.

To recap: You can leave minAabb, maxAabb empty when defining your
particles, and see if you are happy with the visual output of the
PotentialBlockVTKRecorder (or else use the
export.VTKExporter.exportPotentialBlocks to visualise the exact particle
geometry in VTK, which does not use these parameters) and as long as
AabbMinMax=True, the Aabb used for primary contact detection will be
calculated automatically from the particle vertices and orientation, at
each timestep.

Hope this helps,
Vasileios

-- 
You received this question notification because your team yade-users is
an answer contact for Yade.