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				Polywell particle simulation
				Posted: Wed Jul 18, 2012 10:52 pm
				by Johnb003
				I'm writing a particle simulation which I will make open source, designed to test electron confinement and see if I can reproduce the whiffle ball effect which chokes off the point cusp funnels.
I already wrote a version on the CPU that was really slow, and I'm porting to CUDA right now.  I have all the math worked out so it's progressing pretty quickly, but it's still a WIP.  I posted a video of my early results here:
http://www.youtube.com/watch?v=UfHXKUrb-as&hd=1 
			 
			
					
				
				Posted: Thu Jul 19, 2012 4:24 am
				by DeltaV
				You and happyjack27 need to coordinate/consolidate state variables, parameters and initial conditions, then both do runs for the same input vectors/time steps and compare results.  
Without real lab data available, the more simulations the better.
			 
			
					
				
				Posted: Thu Jul 19, 2012 7:01 am
				by Johnb003
				Good idea. I didn't know another person working on a simulation.
I will wait until I have my n-body interactions to collect data though.
			 
			
					
				
				Posted: Thu Jul 19, 2012 9:12 am
				by vernes
				work faster!
			 
			
					
				
				Posted: Fri Jul 20, 2012 8:08 pm
				by happyjack27
				i started out w/nvidia's n-body sample and modified it to do EM-calculations instead of gravity ones.
if you get stuck on anything, you can check my code on sourceforge: 
https://sourceforge.net/projects/em-nbody/
the compute kernel is in "bodysystemcuda.cu":
http://em-nbody.svn.sourceforge.net/vie ... iew=markup
but be ware lest you copy any unknown bugs...  more scientific to do it independantly.
i watched the video.  looking good!
 
			 
			
					
				
				Posted: Fri Jul 20, 2012 8:21 pm
				by happyjack27
				oh, no n-body interactions yet.
that explains why the video was so much faster than mine and appeared to have different dynamics.
(whew! ...i thought i had done something wrong for a second, there!)
			 
			
					
				
				Posted: Fri Jul 20, 2012 8:38 pm
				by happyjack27
				also, you seem pretty smart and like you'd share my interests.   if you want to check out an evil distraction, i came up with an idea that can possibly decrease the computational time complexity of n-body problems with only a small impact on accuracy.  you can check out the basic idea here:  
http://kevinspublicstuff.wikidot.com/petrock
it's sort of like going from a lagragian description to a multi-scalar eulerian description ( 
http://en.wikipedia.org/wiki/Lagrangian ... flow_field )  and back.
an advantage over a barnes-hut tree code is that due to the much more regular data access pattern, it scales a lot better on data-parallel processors.
i came up w/it when working on my swarm wars project ( 
https://sourceforge.net/projects/swarmwars/ ).  i ran into a practical population limit due to n x n inter-organism interactions.  but i needed the population size to be dynamic and practically unlimited.  when i came up with the solution i thought it was an awesome idea.   and could have practical implications for scientific modelling.  i havent gotten around to fully implementing and testing it in swarm wars yet. (i've been doing some other improvements instead.)
 
			 
			
					
				
				Posted: Sat Jul 21, 2012 6:42 pm
				by happyjack27
				i just moved the above mentioned swarmwars over to github:
https://github.com/happyjack27/SwarmWars
i haven't been happy w/sourceforge.  interface is kinda kludgy.  (Though i'm not all to impressed w/github search and advertising features.  kinda feels like i'm moving into a black hole.)  might eventually move tsunami and em_nbody over there, too.