Question #701259 on Yade changed: https://answers.launchpad.net/yade/+question/701259
Status: Open => Answered Jan Stránský proposed the following answer: Hello, > I am ... a new member of this forum. > I just started using YADE and more generally DEM welcome :-) > I am supposed to generate an isotropic pressure which should not change the void ratio of the cell. it depends on definition of void ratio or definition of values from which it is computed. If you apply pressure / velocity gradient, the total volume of the cell is changing, so intuitively also void ratio would change. > I computed void ratio = 0.91 how? A MWE (see below) would help > 1) therefore, is it correct to affirm that I could have a regular packing with any isotropic pressure I decided ? yes, you can have a regular packing with any (reasonable) isotropic pressure. Reasonable = e.g. with linear contact law (e.g. Law2_ScGeom_FrictPhys_CundallStrack) the pressure is limited by stiffness (with higher pressures resulting in degenerated collapsed "one-sphere" packing) > 2) then, after reaching the target isotropic pressure,, I tried to apply an ideal shearing by O.cell.velGrad=Matrix3(0,rate,rate,rate,0,rate,rate,rate,0), imaging that this deviatoric component will produce compaction without changing the isotropic component. But I obtained the opposite effect, the void ratio did not change, whilst the mean pressure did increase. Why so? ideal shearing ... compaction ... isn't it contradicting? Void ratio does not change, because total volume does not change (because of ideal shearing). To help you why the pressure increased, we would need a MWE (see below). > 3) if so, I would like to obtain the desired void ratio at a given isotropic pressure without changing the particle radius. What is the best approach? Depending on definition, but I feel like one of the values is dependent on the other. I.e. you cannot independently vary pressure and void ratio. Cheers Jan PS: also please read [1] and consider point 5 and consider providing a MWE. [1] https://www.yade-dem.org/wiki/Howtoask -- You received this question notification because your team yade-users is an answer contact for Yade. _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp