Re: Difficult geometry problem -- tentative resolution

From: Joseph Comfort <>
Date: Tue, 15 Jun 2010 11:47:10 -0700

Hi Vasilis,

We are all scientists trying to solve problems. Your message did not
specifically identify the 'logical errors' and so was not entirely helpful.

I can assure you that I spent a huge amount of effort (and frustration)
trying to debug the geometry, and only submitted a message when I
concluded that additional sets of eyes should be helpful.

Now we have a problem. The .inp file from which you started was
attached to one of my messages as a limited one for my geometry, but one
that worked. I just tried it again, and it works. But the input file
you attached bombs!

So what are the differences? You changed my RPP blackhole to a SPH.
OK, and not an issue. Otherwise the definitions of the bodies were left
unchanged. OK. The differences are in the definitions of the regions.
1) You subtracted a list of bodies (Fiduc to VacDet2) from the body
World. This is unnecessary because they are all contained within the
body of ChamHol. The other region of space that is subtracted away to
form the World region contains ChamHol. However, I checked and the
redundant subtraction does no harm.
2) The real error is in your modification of the region HolColl. You
added a +CuColl. The region is entirely defined by the HolCol body and
can stand alone. Your change led to immediate execution failure, with
geofar messages and the array dumps. Logically, I am not sure that it
should fail, but it certainly does.

I have only recently started to use flair and, for me, it has limited
appeal. There are also a few things I don't like.
1) If a job is 'Run' with flair, the input file is modified. Sometimes,
I am happy with how I have formatted the input file and do not want it
changed. The changes make the file harder to read and are less
2) I found that flair continues to read input cards and work with them
even after a STOP line. I can understand the reasons, but it is harder
to get a simple plot of the geometry soon after GEOEND without worrying
about the rest of the file.
3) I have had problems with plotting or not plotting a region that has
the same material (e.g., air or vacuum) as the area surrounding it. The
control on the PLOTGEOM card does not seem to work as it reads to me,
and I have to change the ASSIGNMAT cards. Maybe nothing can be done, or
maybe it is just me.

If you are developing easier and better ways to provide input for Fluka,
as Alberto indicates, I'll look forward to them.

Thank you,

Vasilis Vlachoudis wrote:
> Hi Joseph,
> you have logical errors in your geometry.
> Find attached the modified input file correcting these problems.
> Please next time before submitting a geometry problem try to debug it
> properly.
> V.

Joseph Comfort                      Phone: (480)-965-6377
Physics Department                  Dept.: (480)-965-3561
Arizona State University            Fax:   (480)-965-7954
Tempe, AZ  85287-1504               Email:
Received on Thu Jun 17 2010 - 11:53:32 CEST

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