LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Mailing List Archives
Re: [lammps-users] Shear Flow of non-spherical particles
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [lammps-users] Shear Flow of non-spherical particles


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Thu, 18 Dec 2014 09:37:13 -0500

On Thu, Dec 18, 2014 at 5:39 AM, Sina Haeri <s.haeri@...652...> wrote:
> Dear lammps users,
>
> It sent this message yesterday but seems that the email was not sent
> correctly and the thread is empty. So I am sorry if you are recieving
> this for the second time.

i am now seeing it for the third time.

the thread is empty, because nobody felt compelled to answer. please
note that this forum is a volunteer effort, so there is no guarantee
for an answer, especially on a topic that not many people are familiar
with (like me).

if i had a guess, i would think that your understanding of what is a
large or small shearing rate is different from what fix deform does.

axel.


>
> I'm trying to simulate shear flow of non-spherical
> particles (dumbblle shape) using fix rigid and granular package
> (version: 9-Oct).
> The particles are create from two overlapping spheres (see attached
> figure) and initially configured in a 25x25x25 lattice (using pizza.py)
> with a vol fraction of 0.6
>
> I am using the following script for my simulation
>
>
> units           si
> atom_style      sphere
> boundary        p p p
> newton          off
> comm_modify     mode single vel yes
>
> #Read the Cluster of compound particles and add mol property
> fix                  addMolecule all property/atom mol ghost yes
> read_data       dumbells.dat fix addMolecule NULL Molecules
>
> #Relax the particles
> pair_style      gran/hooke/history 2000 NULL 50 NULL 1 0
> pair_coeff      * *
>
> velocity        all create 1e15 1234 loop geom
>
> neighbor        0.003 bin
> neigh_modify    delay 0 every 1 check yes
>
> timestep        1e-5
> fix             1 all rigid molecule
>
> run 30000
>
> #Remove Previous Settings
> unfix        1
> uncompute    1
> uncompute    2
>
> reset_timestep    0
>
> #New Seetings
> change_box    all triclinic remap
>
> pair_style      gran/hooke/history 2000 NULL 50 NULL 0.5 1
> pair_coeff      * *
>
> timestep    1e-5
>
> fix        1 all rigid molecule
>
> fix         shearRun all deform 1 xy erate ${shearRate} remap v units box
>
> run ${NSTEPS}
>
> I expect to get a linear velocity profile but I get an S shape profile.
> This is independant of the time step size. I have attched velocity
> profile results for three different shear rates. At very low rates
> (${shearRate}~1) the profile is almost linear but this quickly changes
> to an S shape by slightly increasing the shear rate (${shearRate}>2).
> The simulation also seems to have reached steady state since I tested it
> with two different ${NSTEPS} with larger nstep twice the smaller one.
>
> I appriciate any ideas or suggestions from the developpers or the community.
>
> Regards - Sina
>
>
> untitled.png
>
>
> twoParticle.png
>
>
> --
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>
>
> ------------------------------------------------------------------------------
> Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
> from Actuate! Instantly Supercharge Your Business Reports and Dashboards
> with Interactivity, Sharing, Native Excel Exports, App Integration & more
> Get technology previously reserved for billion-dollar corporations, FREE
> http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk
> _______________________________________________
> lammps-users mailing list
> lammps-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/lammps-users
>



-- 
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.