> We didn't compare with other methods, because we have just this one > currently implemented. Some papers about SAP (see SIGGRAPH papers, > they are cited in our publications about yade) say that it's really > fast :) That's why we used it. But WE don't have a comparison with > others.
We don't have comparisons because no-one cares about performance. Try running the same large scenario with esys-particle, pfc3d and yade and you will see the difference. Grid colliders ARE MUCH FASTER, at least in terms of scalability, and I repeatedly suggested on the list that it would be a nice project (for diploma thesis perhaps) to implement it. Once that is right, domain decomposition is actually quite easy and so on. The current collider (InsertionSort, which is PersistentSAP, but faster and cleaner implementation) is O(N^2) for the initial sort and around O(N log N) for the subsequent steps, depending on the packing motion also. This really prevents yade from being used on large packings (>10^5), even with fast machines. Esys-particle uses domain subdivision & grid collisions and (they say) it takes around 10% of total simulation time, regardless of the number of particles (scales O(N); see e.g. Munjiza NBS algorithm and http://www3.interscience.wiley.com/journal/112140923/abstract I mentioned earlier; esys-particle uses something similar). Chiara hit the most weak (IMO) point of yade, the collision detection: scales badly and is not parallelized. It is a serious issue that will have to be dealt with, sooner or later. Cheers, Vaclav _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
