Gravity Simulator http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl General >> Discussion >> Parker Simulation accurancy http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1168036790 Message started by frankuitaalst on 01/05/07 at 14:39:50

 Title: Parker Simulation accurancy Post by frankuitaalst on 01/05/07 at 14:39:50 Wondering how accurate the Parker Simulation could be I ran some easy to interprete simulations . As in Parker the time-step can be  rather big ( up to 1/2 year in the case of earth orbiting the sun ) , and depends upon the accurancy wanted , I ran some simulations with decreasing accurancy . In each simulation hereafter I put the Earth in a perfect circular orbit around the sun at 1AU , and calculated the minimum and maximum distance to the sun at the end of each interpolation . These results are also plot on the screen. For simplicity I rounded the distance to an INTEGER . I always stopped the simulation after ca. 5000 years of simulation. Fig 1 was run at an accurancy of 10 meters . http://www.orbitsimulator.com/yabbfiles/Attachments/Eartacc10m.jpgFig 2 was run at an accurancy of 100 meters . http://www.orbitsimulator.com/yabbfiles/Attachments/Earthacc100m.jpgFig 3 was run at an accurancy of 10000 meters (10 km ) http://www.orbitsimulator.com/yabbfiles/Attachments/Earthacc10000m.jpgFig 4 was run at an "accurancy" of 100.000 meters ...(picture is too big to post ) , but max rises up to 10004 und min goes down to 9995 ... As one can see the simulation is quite stable up to an accurancy of 10.000 meters per interpolation . The accurancy at 5000 years is maintained up to 10-4 !!!At 100.000 meters the accurancy is lost , not quite a surprise .... Due to some transfer and limitations of picture size the image quality of above pictures was reduced

 Title: Re: Parker Simulation accurancy Post by frankuitaalst on 04/23/07 at 10:10:45 As a test of the accurancy of the Parker Integrator the Pluto orbit was run around the sun (no other objects) ; starting "now" for about 16 Mio years . The "accurancy" was set at minimum 10 m per iteration . The program performed 720.000 iterations for this time period . The result is shown hereunder . As one expects that the SMA of Pluto remains equal to the initial value , a measure of the accurancy is the deviation from the initial value . The graph hereunder gives after 14 Mio years a deviation of 200.000 meters (200 km ) , or a deviation of about 0.25 m/iteration .