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Re: [lammps-users] Ncount bin sensitivity
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Re: [lammps-users] Ncount bin sensitivity


From: Steve Plimpton <sjplimp@...24...>
Date: Mon, 3 Jul 2017 17:59:00 -0600

Also, is the total count for all the bins equal
to the total # of particles you expect to be counting?

From one snapshot in a dump file, you should
be able to manually count the particles in the
first/last bin and verify what LAMMPS is counting for the same.
I.e. use fix ave/time with no averaging.

Steve

On Mon, Jul 3, 2017 at 9:40 AM, Axel Kohlmeyer <akohlmey@...24...> wrote:
On Sat, Jul 1, 2017 at 7:41 PM, Roberts, Andrew
<A.P.Roberts@...5884...> wrote:
> Hello,
>
>
> I am new to LAMMPS, but I have generated a Couette flow and the profile is
> almost linear (attached), however the profile is slightly non-linear near
> x=0.1 and 0.9. I noticed that the number of counts (Ncount) is approximately
> half at x=0.1 and 0.9. Is there any reason why there should be a discrepancy
> at the ends of the profile? These are the lines I am using to generate the

my guess would be, that this is likely due to the ordering and
excluded volume near the walls. fix ave/chunk averages over points,
i.e. the position of the center of your particles. just make some
snapshots of your system and check manually.

axel.

> profile:
>
>
> run  100000
>
> compute cc1 flow chunk/atom bin/1d y center 0.05 units reduced
> fix 8 flow ave/chunk 2 50000 1100000 cc1 vx vz norm sample file vel.profile
>
> run  1000000
>
>
> Is there any way to make the number of counts the same in all bins? Or is
> there another reason for the difference - e.g. bin sensitivity? (I think I
> have enough timesteps)
>
>
> Kind regards,
>
>
> Andrew
>
>
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--
Dr. Axel Kohlmeyer  akohlmey@...43...4...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.

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