> I am playing a little bit with the code to understand how thinks work > in terms of energy. I started with a very simple example of two balls > in normal contact. > I am only applying an initial velocity to one particle, hence the > total energy of the system is only given by (kinetic + potential > elastic). > Look at the two attached figures. The first one (dt_crit) is the > result obtained using the critical time step computed by Pwave in > Yade. The second one (dt_Econst) is obtained decreasing the time step > to get the total energy constant.
Hi Chia, very nice plots. What were values of Δt in there two cases? Or rather, what was the Δt_Econst/Δt_crit ratio? (PWave is only an estimate; there is a section on that in my thesis) What is also interesting that in both cases Etot has eventually the same value. > Now I see that the time step influences the solution in terms of > energy and this is just a very little example (so it does not really > quantify anything). However, I have one consideration: does this mean > that we are mainly dealing with non conservative systems in our dem > simulations? Is this the right way to compute the total energy? I > guess what happens in a system with many bodies (I am gonna try).. Speaking of myself, I never measured the energy. Besides fear of never getting constant total energy ;-) I was mostly using some fixed particles, viscosity etc and didn't bother to compute energy dissipation. Doing this kind of studies might be tremendously useful, though. I am sure it will reveal a whole pile of physically questionable things. Best regards, 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
