Implementation of JKR cohesion model

Submitted by nquangd on Wed, 07/10/2013 - 11:21

Hi all,

I modified the pair_gran_hook/hertz history style to take into account the Van der Waals adhesion force following JKR model. The model is described in this paper where
Fn = F_adhesionJKR + F_damp

The simulation is able to run, but I got unreasonable results. I find it was caused by the formulation of "ccel" in LIGGGHTS that I used. Currently, I use the expression:

ccel = - F_adhesionJKR - F_damp

where F_adhesionJKR is defined to be positive when it pushes two particles toward each other.
F_damp is calculated as in original LIGGGHTS
I am confusing about this. Would you have any idea for the right expression of ccel in this case to adapt the JKR model with LIGGGHTS?
Thank you very much!

Best regards,


ckloss's picture

ckloss | Fri, 07/12/2013 - 14:23

Hi Duy,

it's hard to give advice without looking at code
please note that LIGGGHTS performs "ccel-=Fn_coh*rinv;" to get the dimensions correct
if you debug this step by step (e.g. with fprintf statements) , it should be pretty straight-forward to resolve