yade-users team mailing list archive

["Christoph Kloss" <christoph.kloss@xxxxxx>]

Hi Feng, dear Yade community,


@Feng: Thanks for the link to your homepage. It is interesting to
know that somebody already did something similar :-)

Btw: Is it correct that Yade is based on a shared memory approach?

>I think you and I should be using the same approach originated from Prof.
Tsuji?
Yes!

>1. FVM size/particle size

The simulations I did so far were with particle diameter in the same order
of
magnitude or smaller than the grid spacing.
I did not extensively test particles that are much larger than the grid size
because my flow problems did not involve such cases. 
But to my knowledge, this would lead to a) convergence issues and b)
possibly malpredictions of the dragforce by standard drag correlations 
(Gidaspow, DiFelice,...)
My maximum ratio cell spacing/particle diameter was ~1/1 which converged and
matched the validation experiments well


>2. The maximum particle number possible on a cluster

It depends on what cluster you have :-)
If you look at http://lammps.sandia.gov/bench.html#chute
you fill find the rightmost dot in the left figure corresponding
to 2 BILLION PARTICLES!


>3. The parallel mechanism

We are using MPI because we think that the code should be portable to
clusters.
We have a small cluster (~150 proc.) at our Institute, so for me it is a
huge speed-up 
switching from my workstation to the cluster


>4. What kind of problem/type of flow you use in your problem?

Typical problems that we are using or intending to use CFD-DEM for is
pneumatic conveying,
fluidized bed, hopper discharge and die filling.


>5. Is it easy to change/create new particle constitution laws for the solid
phase?

Yes, LAMMPS is written in the intention to be easily modified. A whole
section
of the documentation is dedicated to this:
http://lammps.sandia.gov/doc/Section_modify.html
I must admit that currently, LAMMPS is missing a feature to import granular
walls from
CAD. But I am working on this...


>6. Effect of different drag equations

I must admit that I did not extensively test that. Afaik, Gidaspow could
lead to 
convergence problems as it is discontinuous in one point. Thus I also used
DiFelice
but did not find much difference


I should add that the simulation experience I am talking about was with a
EDEm-FLUENT coupling
that I wrote myself. The "LammpsFoam" is now in beta, and this fluidized bed
configuration
http://lammps.sandia.gov/movies/gran_openfoam.avi
is the only case that we calculated with "LammpsFoam" so far.


@Feng: It would be nice to know what answer you would give to these 6
questions!



Thanks and regards,

Christoph



-------------------------------------------------------------------

Von: Feng Chen [mailto:fchen3@xxxxxxx] 
Gesendet: Donnerstag, 08. Oktober 2009 02:18
An: kloss@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx;
yade-dev@xxxxxxxxxxxxxxxxxxx; yade-users@xxxxxxxxxxxxxxxxxxx
Betreff: RE: [Yade-dev] Open Source DEM with LAMMPS

Hi, Christoph Kloss:

I am so glad to see there is another code for DEM-CFD coupling since this
has been my PhD topic, I also coupled YADE with OpenFOAM:

http://fchen3.googlepages.com/discreteelementmethod

I think you and I should be using the same approach originated from Prof.
Tsuji?

I would be very like to discuss some of the details with you, such as:

1. FVM size/particle size
2. The maximum particle number possible on a cluster
3. The parallel mechanism
4. What kind of problem/type of flow you use in your problem?
5. Is it easy to change/create new particle constitution laws for the solid
phase?
6. Effect of different drag equations

etc.

Thank you for sharing your experience with us!!!

Feng Chen

-----Original Message-----
From: yade-dev-bounces+fchen3=utk.edu@xxxxxxxxxxxxxxxxxxx on behalf of
Christoph Kloss
Sent: Wed 10/7/2009 6:11 AM
To: yade-dev@xxxxxxxxxxxxxxxxxxx; yade-users@xxxxxxxxxxxxxxxxxxx
Subject: [Yade-dev] Open Source DEM with LAMMPS

Dear yade users and developers,

I would like to bring the DEM capabilities of LAMMPS to your attention.
LAMMPS is an open source
molecular dynamics code that also provides possibilities for DEM simulations

(thanks to algorithmic and physical analogies). LAMMPS is on the open source
"market" since the mid90s.
It is thus quite mature, very fast and provides excellent documentation.

Please refer to the homepage http://lammps.sandia.gov/ for download and
documentation.

For some simulation examples, please refer to
http://lammps.sandia.gov/movies.html#dem

The final movie ( http://lammps.sandia.gov/movies/gran_openfoam.avi ) shows
a new capability that
my colleague Christoph Goniva and I have developed to perform CFD-DEM
simulations by coupling LAMMPS
to the OpenFoam computational fluid dynamics (CFD) package. This allows us
to run CFD-DEM simulations
on clusters using MPI parallelism.

Some more videos and sample input scripts can be found at
http://fluid.jku.at/hp/index.php?option=com_docman&task=cat_view&gid=168

LAMMPS is written in C++ and very easy to modify. If you are interested in
LAMMPS, you are welcome
to contact me! I would be happy if YADE and LAMMPS could profit from each
other.


Kind regards from Austria,

Christoph Kloss

--------------------------------------------------------------------
Dipl.-Ing. Christoph Kloss

Christian-Doppler Laboratory on Particulate Flow Modelling
Institute of Fluid Mechanics and Heat Transfer
Johannes Kepler University,
Altenbergerstrasse 69, A-4040 Linz/Austria

e-mail: christoph.kloss@xxxxxx
phone: +43-(0)732-2468-6476
fax: +43-(0)732-2468-6462
web: fluid.jku.at
-------------------------------------------------------------------




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