I have not seen any recent discussion of units in the granular pair styles, and was unable to find an answer to this question, so my apologies if it has been addressed previously. For most of my granular simulations, I have been using the dimensionless units LJ. However, I have a question about an example file, in.granregion.funnel, that is available on the lammps website (incidentally, who is the author of that file?). The files lists “units si”, and writes all the usual parameters (kn, kt, gamma_n, gamma_t) in terms of the elastic constants (young’s and shear moduli) in these units. But particle radii are 0.5, and the acceleration of gravity is 1. Does this mean that particles have diameter 1m, since we are in SI units? Or is it using non-dimensional units for these in a fashion I have not been able to identify?

Thanks in advance for your help.