Welcome, Guest. Please Login.
Gravity Simulator
11/21/17 at 04:13:03
News: Registration for new users has been disabled to discourage spam. If you would like to join the forum please send me an email with your desired screen name to tony at gravitysimulator dot com.
Home Help Search Login


Pages: 1
Send Topic Print
Question to Tony , GravSim data setup (Read 1869 times)
frankuitaalst
Ultimate Member
*****


Great site

Posts: 1507
Gender: male
Question to Tony , GravSim data setup
09/18/11 at 03:52:13
 
I want to import a large dataset in Grasim and want to do it in the Gravsim file directly , opening it as text .  
I guess I can do it , keeping the headers and insert afterwards the planets data , ending with the foots  
But when I see different original files I wonder how to express the mass ( in what unit ? EarthMass , Sun Mass , kg ..?)
Further I would like to know where to initial time step is set .  
Back to top
 
 
Email View Profile   IP Logged
Tony
YaBB Administrator
*****




Posts: 1051
Gender: male
Re: Question to Tony , GravSim data setup
Reply #1 - 09/18/11 at 11:45:16
 
Quote from frankuitaalst on 09/18/11 at 03:52:13:
I want to import a large dataset in Grasim and want to do it in the Gravsim file directly , opening it as text .
I guess I can do it , keeping the headers and insert afterwards the planets data , ending with the foots
But when I see different original files I wonder how to express the mass ( in what unit ? EarthMass , Sun Mass , kg ..?)
Further I would like to know where to initial time step is set .

 
This depends on the version you're using.  See http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1131749461/3#3 for an explanation of the gsim file.
 
Time step is the 3rd piece of data after the <SData> tag.
Simulations in all but the most recent beta versions (~May 2011 - present) record mass as EarthMass * timestep^2, which reduces to EarthMass if your time step is 1.  Newer beta versions abandoned this to make the program more compatible with future integrators that have dynamic time steps.  In the older versions, velocity is (m/s)*timestep.  This too is abandoned in the newer versions.
 
The 7th piece of data after the <SData> tag tells it how many objects are in the simulation.
 
 
How many objects are you importing?  Remember, Gravity Simulator slows to a crawl when the nunber gets into the high hundreds.  I've got a few stand-alone programs which were never released that help create .gsim files from text files of orbital elements or vectors, so if you want sme help, let me know.
Back to top
 
 
Email View Profile WWW   IP Logged
frankuitaalst
Ultimate Member
*****


Great site

Posts: 1507
Gender: male
Re: Question to Tony , GravSim data setup
Reply #2 - 09/18/11 at 12:09:23
 
Thanks Tony for the help .  
What I wanted to do is creating a Gsim which contains  all the extrasolar solar systems whith more then 2 planets .  
I think I have succeeded .  
In total there are about 150 bodies in this system .  
As a pro I included for each system also an Earth planet at 1AU as a reference .  
 
I took the basic data from the extrasolar plantes encyclopedia and  transformed the data in order to fit in the Gsim format .  
However I see I have a problem with planets intersecting with sister planets when dealing with larger eccentricities .  
If I can fix this ( don't  know yet where the error comes from ) I'll post the sim .
Back to top
 
 
Email View Profile   IP Logged
Pages: 1
Send Topic Print