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Re: Uniform distribution



 Actually you can enter a value for StdDev but for R_mean I think you
should do some pre_processings to estimate the R_mean of your pack after
the phase of compaction. 
Taking into account the porosity and the number of spheres you can find
the appropriate value of R_mean and deduce the ratio StdDev that you
have to use to satisfy the range of granulometry. And then on yade just
enter the right dimensions for the box and the number of spheres.

A last thing, you need to check for the porosity given by Yade after the
compaction and it should correspond to what you expect else you need to
change the friction angle of the compaction phase so that your porosity
fits perfectly.

If something goes wrong with this procedure, or may have impact on the
results, don't hesitate to mention it !


Le mercredi 13 janvier 2010 à 17:11 +0100, Chiara Modenese a écrit :
> Hi all,
> perhaps (but I could be wrong) I found an error in the generation of a 
> uniform distribution of radii used in Yade.
> As some have already pointed out in 
> previous emails the uniform distribution is such that:
> R_min = R_mean * (1-
> StdDev)
> R_max = R_mean * (1+StdDev)
> In Yade we define a StdDev and a R_mean 
> and with such values we generate the distribution but if I check the results in 
> terms of R_max and R_min, I do not see a correspondence with the values I 
> should obtain as performed above.
> Moreover I have tried to see if the 
> distribution is uniform between the values of R_max and R_min I obtain from 
> Yade and actually between them the distribution is not uniform. So, what's 
> wrong here?
> I need to use a uniform distribution, I have tried to look at the 
> possible available distributions in boost but what I need is that one used in 
> Yade (boost::uniform_real<>(0,1)) that to me doesn't work properly and I do not 
> understand why.
> Any suggestions? 
> Thanks a lot,
> Chiara
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