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Message started by looseskrewz on 04/20/07 at 13:55:56

Title: Hey guys - New here
Post by looseskrewz on 04/20/07 at 13:55:56

Hello everyone.

New to the board but not to gravity simulators.....always scanning the web for new ones.

Although I have found this one to be one of the best...if not the best...without getting into all the compiling and whatnot.


Anyhow, what are the best settings and speed to run a simulation at without causing false trajectories?


Oh, and is there somewhere that keeps track of the number objects that you have?
...I started two galaxies, and it would be cool to know how many objects there were when I started, and how many objects there are now.

Thanks


Title: Re: Hey guys - New here
Post by Tony on 04/20/07 at 14:12:54

Welcome.

The best speed varies from simulation to simulation.  There's lots of discussion in this forum board on the topic.  Frank is running the outer solar system only because deleting all the tight orbits allows him to speed up the simulation considerably.

Basically, you want duplicate results using different time steps.  If you have a time step of 32K and you re-run your sim at 16K and you get different results, then you were running too fast.

But it all depends on what you're after.  For example, the simulation "onlyplanet.gsim" which is the first simulation you should see after a fresh install of Gsim 2.0 plots the solar system on your screen.  It contains all 7 planets plus Pluto and Earth.  It does a nice job showing you the scale of the solar system and the shapes and orientations of the orbits.  Since this was the goal of the simulation, the choice of time step was appropriate.  But if you wanted to predict where Mercury would be 200 years from now, this simulation is run much too fast.  You would want to start fresh with "fullsystem.gsim", delete the unwanted objects, and run it at a very slow time step (perhaps 16 seconds).  But this slow speed would cause anyone wanting to see a quick solar system demo to quickly lose attention.

There's pleanty of threads where time step is discussed, and its a learning process for us too.  So feel free to contribute to the discussion.  Try the latest beta version (see beta thread) too.  It seems to be stable and offers some nice improvements over 2.0.

Title: Re: Hey guys - New here
Post by looseskrewz on 04/20/07 at 17:47:14

Thanks for the info!

I already found the newest beta. :)

As of the moment, I am working on simulating a collapsing gas cloud just to see what forms from it.....will take a very long time, but may be worth it!

It is a great piece of software, I hope that Tony continues to work on it.

Very interesting stuff.

Title: Re: Hey guys - New here
Post by looseskrewz on 04/20/07 at 17:52:18

Another question I have is:

Is there a breaking point (distance) for the influence of a gravitational pull?  (computer simulation wise)

Title: Re: Hey guys - New here
Post by abyssoft on 04/20/07 at 18:17:36

No true Breaking point that I am aware of and if there is one it is beyond the distances involved in the extapolated Universal distances IE Greater then 150 Glyr.
Becare full if you are doing gas clouds most high end systems can only handle  2-3 K objects

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