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Re: [Question #698392]: I calculated the kinetic energy by E=0.5mv^2+0.5Iw^2 but it is not equal to kineticEnergy() when O.cell.velGrad is set


Question #698392 on Yade changed:

    Status: Answered => Open

Yuxuan Wen is still having a problem:
Hello Jan,

Thank you for you help and sending me the position of the source code! I
am much appreciated!

But I am still a little confused with the definition of the fluctuation velocity. As you said, the E=0.5*m*v^2+0.5*I*w^2 still holds, and "v" and "w" are the fluctuation velocity . In the source code, the fluctuation velocity is defined as:
bodyFluctuationVel(state->pos - state->vel * scene->dt, state->vel, scene->cell->velGrad)
which is a function of 1)updated position, 2) v, and 3) velGrad. 
But I don't know how to calculate the fluctuation velocity by these 3 terms. I searched the documentation by "bodyFluctuationVel" and didn't find anything matched.  I wonder if it is possible that you could tell me the expression of the fluctuation velocity? Thank you!

Kind Regards,

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