[Beowulf] Physics Problems for Beowulf

[Joe Landman]

Hi Timo:

Timo Mechler wrote:
> Hello all,
> 
> Over the past couple years I have done research one Beowulf clusters and
> also implemented the first one at my school.  Now that I'm getting closer
> to graduating, I'm looking of turning all this work into a senior project.
>  The only part that's missing though, is a good physics problem that I
> could code up a numerical solution for and run in parallel.  I have done
> some of this, but it's mostly been simple stuff, such as a simple
> numerical integration via the Monte Carlo method in parallel.  I know some
> of you on this list are professors and professionals that have extensive
> physics knowledge.  What sorts of physics problems would you suggest I
> might be able to code up that would take a some time run on a Beowulf
> cluster?  I'm going to be using Fortran 77 with MPI libraries as my base
> for coding.  Thanks in advance for your help on this, I appreciate it.

A problem I coded up for a class I teach on HPC applications is an ideal 
gas in a 2D box, with correct (momentum conserving, energy conserving) 
dynamics.  It was done in C though.  I might suggest something like 
this.  Then you can measure pressure (number of impacts on perimeter 
wall per time step), temperature, and volume, and do experiments where 
you suddenly double the volume, or have one of the wall boundaries start 
creeping downwards to decrease the volume, or chill the walls, so that 
upon collisions with the walls the atoms get slower/faster (lose/gain KE 
to/from the reserviour).

I did this as an example that I wanted them to add in how to move atoms 
between processors (no periodic BCs, just "partitions" that atoms can 
cross.  And if they cross it, you need to move them to the adjacent 
processor.

I have done up to about 1 million "atoms" on a 32 way run, and it works 
pretty nicely.  Somewhat hard to visualize the output, so I had it write 
stuff out in ".xyz" format, and used VMD to generate a movie.  You can 
see it (about 100 atoms, tiny interaction radius, and a few thousand 
steps) here at http://www.scalableinformatics.com/public/idealgas.mpg .

Joe

> 
> Best Regards,
> 
> -Timo Mechler
> 
> 

-- 
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
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