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,