Hi Vaclav, why not trying to calculate the velocities at the right time? I remember I was doing it and energy was conserved (without damping, either local or global). We just need to shift them by adding acc*dt/2 (btw, we need to _subtract_ this term in order to shift in the right way, as discussed with Bruno on the list). It is worth a try. However, reducing the time step should help, if we do not apply the shift.
Chiara PS nice idea to track energies in this way 2010/11/13 Václav Šmilauer <[email protected]> > > I am not sure about the cause; two possible explanations come to mind (i) > mid-step values of velocity vs. on-step accelerations etc. and (ii) without > damping, many elastic collisions take place (their number increases if > damping is small, as the system never goes to quasi-static state) and > integration error accumulates (what contradicts this is that the precision > would be increased with smaller dt, which is not the case, and also that the > imprecision effects would cancel each other in average). > > Could someone have a look at the code and suggest something? > > Cheers, Vaclav > > _______________________________________________ > Mailing list: > https://launchpad.net/~yade-dev<https://launchpad.net/%7Eyade-dev> > Post to : [email protected] > Unsubscribe : > https://launchpad.net/~yade-dev<https://launchpad.net/%7Eyade-dev> > More help : https://help.launchpad.net/ListHelp >
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