Damping: no, PFC and YADE's global damping implementations are not exactly the same, because PFC uses v(t) while Yade uses predicted v(t+dt/2) to define the sign of the damping force.
I think it is generally pointless to compare results including some damping (local or global) if the objective is to compare constitutive laws and dynamic behaviour. It will usually ends like here, wondering what is the equivalent mass of static+dynamic interaction. A question unrelated to the initial problem and without clear physical meaning, since such dampings are numerical tricks. Damped simulations should only be compared for quasi-static evolutions. The most interesting result above is IMO: case3: no damping at all YADE: flyback_height = 0.133156194762 PFC (notension on): flyback_height = 0.1329 PFC (notension off): flyback_height = 0.1329 There is a 0.2% difference... I would say the two HM implementations are equivalent (at least for the normal force) and that differences in other parts of the code explain the 0.2%. For better understanding, it would be good to compare step-by-step positions and forces. -- You received this bug notification because you are a member of Yade developers, which is the registrant for Yade. https://bugs.launchpad.net/bugs/806944 Title: different behavoir of Hertz model while comparing PFC and YADE Status in Yet Another Dynamic Engine: New Bug description: Hello, During verifiing my model I compared output from PFC 4.0 with the output from YADE (bzr2877 on Debian Squeeze 64bit). There I found a different behavior between these two programs. I dont know if this is a bug or not, but I hope someone can explain the different behavior. The model itself is very simple. There are two spheres, an upper one and a lower one. The lower one is fixed and the upper one is falling down to the lower one, collides and jumps back. The value of interest is the flyback height of the upper particle. In PFC I measure higher values of flyback height, then in YADE (see log-files in the attachment). Can someone tell me why there is a difference in the flyback height? (input parameters are the same for both programs ... see caller_two-spheres-jumping.dat for PFC and two-spheres.py for YADE) Regards, Christian Jakob To manage notifications about this bug go to: https://bugs.launchpad.net/yade/+bug/806944/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~yade-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-dev More help : https://help.launchpad.net/ListHelp
