> this should be easy in yade, but I can't spot the easy solution that > must be there. I have beads in a container. I want to model their > friction against it's walls. I can get the friction of the beads > themselves by measuring the angle of internal friction. assuming I > know the poissons ratio and young's modulus, I am set. but for the > walls, it is a different story. is there no way to simply specify the > coefficients of static and kinetic friction of the wall material? or > do I have to measure the angle of internal friction of beads made with > the same material? also, how do I take into account that the > coefficients of friction between, say, glass and teflon, teflon and > teflon, and glass and glass, are all different, for both the cases of > static and kinetic friction? > > I feel i'm pushing it a bit, but these also seem valid questions when > it is taken into account that this program operates at timesteps of > e-6 seconds, and therefore necessarilly takes into account a great > deel of physics.
Hi Mike, Material and Shape are orthogonal for each body, so you can specify friction coefficient for wall as for any other body. A different question is how is the friction coefficient translated to some parameter of an interaction. The way it works is that InteractionPhysics is created via Ip2_* functors which typically compute something from two Materials (averages for Young's moduli, for instance). To have all the combinations you need, if there is no explicit formula that is common (such as always taking the average or minimum value), you can proceed in two ways: 1. Create a new Material sub-class for each type of particle, then Ip2* functor for each admissible combination, each containing a special algorithm that will do whatever you want. A little overkill perhaps, but it will work. 2. Create one new Material which will contain something integer identifier of what kind of material it is supposed to represent. Then one new Ip2* functor will switch the algorithm based on the combination of identifiers. (Anton uses this approach to make the difference between interaction of particles within one grain and particle where each is from different grain in his RockPM classes IIRC). Yo ucan describe your needs in more detail if you feel you need more information to get started. We are here to help you coding your new classes if you need them. There is no performance penalty for that, it will be as fast as those that exist, and we can write some of that code for you -- everybody has the experience it is harder the first time, but it is really not complicated. HTH, Václav _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
