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[Chareyre <question178830@xxxxxxxxxxxxxxxxxxxxx>]

Question #178830 on Yade changed:
https://answers.launchpad.net/yade/+question/178830

Chareyre posted a new comment:
I was checking again your script Jakob. It seems there is a small
mistake here:

        Vd_classes[ii]  = (Vg_borders[ii+1]+Vg_borders[ii])/2.0         #average volumes in every class
        rad_d[ii]               = pow(3*Vd_classes[ii]/(4*math.pi),1.0/3.0)             #average radii in every class
        num_spheres[ii] = int(round((3*V_classes[ii])/(4*math.pi*rad_d[ii]*rad_d[ii]*rad_d[ii])))

This is assuming that the average of (x^3) is (the average of x)^3, which is not true. It results in a shifted PSD.
If the size interval is very small, the error vanish, else there is an error. OTOH, this effect is accounted for in makecloud() (which also allows per-number distribution in addition to per-volume).

I understand there is no point for you to learn using makeCloud if you
want to keep the exact same procedure as in PFC, but it is not a reason
to keep your script in Yade's trunk. makecloud() is a one-line command
and is more versatile and robust. The same remark holds for particles
growth via triax engines, which should be prefered by anybody who don't
come with his own predefined algorithm.

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