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Re: [Question #694886]: set a velocity from zero to a certain value

 

Question #694886 on Yade changed:
https://answers.launchpad.net/yade/+question/694886

    Status: Needs information => Answered

Robert Caulk proposed the following answer:
If you are referring to how a particle can at one time-step in Yade have
a velocity of 0 and at the next time-step have a user assigned velocity
of V, then you probably need a quick lesson of how Yade integrates
particle movement through time.

Have a look at the description of how Yade explicitly integrates
particle motion through time using forces [1], and you will realize that
in between steps you could simply add a velocity to a particle and it
will be reflected in the next time-step. In [2] you see the new velocity
is added to the existing velocity state that you would have set manually
between steps. Then [3] occurs for the updated particle position. So if
you have no acceleration due to forces or gravity in your scene, then
the velocity will simply be your user assigned velocity.

In other words, there is no ramp for user assigned velocities.

[1] https://yade-dem.org/doc/formulation.html#motion-integration
[2]https://gitlab.com/yade-dev/trunk/-/blob/master/pkg/dem/NewtonIntegrator.cpp#L245
[3]https://gitlab.com/yade-dev/trunk/-/blob/master/pkg/dem/NewtonIntegrator.cpp#L310

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