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Re: clumps


I am sorry to ask a novice question again.. Assuming that this equation (I dw'/dt + [w' cross Iw']= T') is going to be used, all viarables are in the local frame and the inertia matrix will be aligned to the principal axis. Since inertia can be represented by a vector, does the Inertia 3x3matrix need to be generated?
But I have a doubt now : what is the definition of w' or w'' in the local frame? Don't we have by definition w=w'=w''=0 in a frame attached to the body? Probably just my imagination...

In this case, only variables that have to be transformed from local to global coordinates (vice-versa) are the angular velocity (w), angular acceleration (dw'/dt) and torque(T)?
"In this case", I think you are right.

Btw, is this problem with Newton's Damped Law only? Or YADE does not yet implement the 'accurate' method to calculate the dynamics non-spherical particles?
Not implemented accurately. Sufficient for you or not depends what you want to simulate.
P.S. I am interested in this because of the ellipsoid. I'll look at superquadratics too (after days of deciding). The thing is i'm stuck at quarternions & rigid body dynamics. <sigh>
Give superquadratics the inertia of spheres, they won't complain. ;)


Yours sincerely, CW Boon

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