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Message #04109
Re: [Question #142804]: PSD generation
Question #142804 on Yade changed:
https://answers.launchpad.net/yade/+question/142804
Status: Open => Answered
Chiara Modenese proposed the following answer:
Hi Bruno,
See below for my answers to your questions.
(1) I will try to summarize them here, though there is some documentation in the code:
 makeCloud() has in fact three possibilities: you can obtain a uniform distribution by starting from either radius mean or porosity as input (and the number of balls, ofc) or you can define psdSizes and psdCumm and in that case you should obtain the distribution as you input it. To be honest I would use particleSD for the latter since I do not remember if makeCloud() was working properly in that sense (Vaclav?).
 particleSD() and particleSD2() do essentially the same job. The difference is that in the first case you guess the volume of solids by the number of particles and the mean radius; this means that if your size distribution is rather broad then the final number of balls you obtain is not the same one as you input. Instead, using particleSD2() you will get the same number of balls because in fact the volume of solids is not really another parameter but it is sufficient to input number of balls and porosity together with the size distribution (there is a comment in the code about that, I hope it is clear).
(2) I think none of the above would apply to your case. If you choose to
input the percentage of passing that is cumulative so I do not think you
can obtain an interval of radii with zero particles.
(3) Vaclav wrote that function and he can probably give you the answer.
(4) It does apply and makes sense but only if you have the list of radii
so that you can actually choose to start from the bigger size, otherwise
it is random as you already say. Indeed this is what happens in both
function particleSD() and particleSD2() since we have the list of radii
available there (and it makes a big difference if you start placing the
big balls rather than the small ones).
HTH, Chiara

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