Question #210907 on Yade changed: https://answers.launchpad.net/yade/+question/210907
Christian Jakob proposed the following answer: > and anybody has advanced method to generate numerical sample to model real granular sand? Hi wangxiaoliang, I also want to simulate a sand with DEM. So our interests are nearly the same. To generate a sand sample there are (as far as I know) 3 methods: 1. generate with given PSD -> hard overlaps -> calm-function needed 2. radius expansion method -> also calm function needed 3. generation of sample in a higher model -> let particles fall down by gravity (settlement) Every method has advantages and disadvantages. 2. and 3. can be done with makeCloud(). I tried all methods and found, that for my purpose (model of a loose sand) method 3 is the best one. In method 1 very hard overlaps occur after generating the sample and one has to calm particles movements (by setting velocities to zero) for the first steps. I found out, that it can lead to instabilities and unexpected behavoir. So I tried method 2, but I also detected numerical instabilities arising from this method. Also it is very tricky to increase radii from clumped particles (as I have in my model). So now I use settlement method (method 3) and I do not have instabilities any more. But the disadvantage of this method is, that the number of particles (that were generated) are random. Also one can not specify a porosity. One will get loosest packing, when settlement is finished. (But you can use ThreeDTriaxialEngine to get your porosity/packing after the settlement procedure!) For the problem with rolling resistance I use clumped particles and a high friction to get the given repose angle from a pour cone test. So I replace one sphere by hardly overlapping two spheres with same radius to get a "non-spherical" particle (clump). I know thats not the real particle shape, but it is more realistic than pure spherical particles. Regards, Christian. -- You received this question notification because you are a member of yade-users, which is an answer contact for Yade. _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
