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Re: how to run the example files?

 

Peiying Hsieh said:     (by the date of Sun, 7 Mar 2010 12:41:28 -0500)

> Hi, Anton,
> 
> The reason why I am interested in the rod_penetration example is because I
> want to learn how to import stl geometries into yade.  It looks like quite a
> lot has been changed since 0.20-2.
> 
> The case I am interested in solving is the following:
> 
> a cup, 3mm X 12 mm X 40 mm, contains about 50 % of liquid.  In the liquid,
> there are about 1 million para-magnetic particles (1 micro in diameter).
> At time = 0, the para-magnetic particles are randomly distributed in
> liquid.  Then, a permanent magnet is placed next to the cup.  Hence, the
> magnetic field starts to attract the particles toward the cup wall.  I would
> like to know how long it takes to attract all particles to the wall.  The
> cup geometry is not a simple box of cylinder.  So, I need to import the cup
> geometry in stl format.
> 
> I have already calculated the magnetic field (flux and also magnetic force
> field) using a finite element PDE solver, called getDP.  The magnetic field
> is static, not time dependent. Because the particles are para-magnetic, it
> can be assumed that the magnetic force is like external body acting on the
> particles, like gravity, except that the magnetic force field varies with
> space.

Applying such static force (which works in similar way as gravity) is
very simple. You just use the current gravity engine, and replace the
added (constant) force, with a variable force that depends on
particle's coordinates.


> Is it possible to read the magnetic force calculated outside of yade into
> yade?  How to apply the force on the particles?  Because the magnetic force
> varies with space, the force on each particle has to find out from the nodes
> (or cells) where the magnetic force was calculated.

if you have sufficient C++ coding skills, then reading magnetic
forces from external file is very simple for you. It would be not
more than 5 or 10 lines of C++ code.

 
> How to apply drag force on the particles?  Drag force varies with speed of
> the particles.

If depends only on the speed, then it is simple too. Just like you applied
magnetic field, but this time depending on velocity property.

Having said that - I must underline that the difficulty of whole task
depends on your python/C++ coding skills.

If you have 1 year of experience with C++ or python it will be
extremely difficult for you, and it will take you roughly 2 years to
complete. (including time spent to familiarize yourself with the code).

If you have 5 years experience it would be moderately difficult, and
you can do that in 2 to 4 months. Depending on how much time per week
you are actually doing this. (including time spent to familiarize
yourself with the code).

With 10 years of C++/python experience it is a piece of cake and you
can do all that in 50 to 100 hours. (including time spent to
familiarize yourself with the code).

Personally I wonder how "good" are my wild estimates ;-)

> 
> If the problem above is achieved, then, I would like to extend to next step:
> 
> After all particles has been attracted at the cup wall, a small tube comes
> down to near the bottom of the cup, turn on vacuum to "suck" all liquid
> inside the cup out.  I would like to know if the magnetic force is strong
> enough to hold the particles in place.  This will involve coupling yade with
> OpenFOAM (free surface with surface tension effect).  If this is done, I
> will image that, it has to be done on a cluster because this has to be very
> calculation intensive.
> 
> Pei-Ying

The second part seems more difficult than the first one. I'm not
working on the OpenFOAM part, and I'm not working on liquids here.
Also, currently all calculations are done in vacuum.

-- 
Janek Kozicki                               http://janek.kozicki.pl/  |



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