I have a physics problem to deal with, I am asking here because a game developers often uses the efficient method. I have randomly distributed circles interacting to through lennard Jones potential or simply with a bounce back boundary condition to wall of random shape, as of know I am taking a V shaped wall. Please help me to understand an efficient algorithm the game developers uses for bounce back interaction. [![x.periodic,y.wall][1]][1]


 [1]: https://i.sstatic.net/WIhVw.jpg