Reason for full mobilisation in rolling friction epsd

Submitted by jenslaube on Mon, 11/09/2015 - 17:17

Dear LIGGGHTS users,

I would like to use the rolling friction model "epsd" for my simulations of nanoparticles and I would prefer having a damping term also above the full mobilisation torque M_rm. Is there a scientific reason for the damping to be neglected at full mobilisation (f = 0)? I can't find any in the underlying publication "Jun Ai, Jian-Fei Chen, J. Michael Rotter, Jin Y. Ooi, Powder Technology, 206 (3), p 269-282 (2011)". Or is this just due to the implementation? Because then I would simply copy the respective part in the "rolling_model_epsd.h" file and recompile to achieve rolling damping also above full mobilisation.

Best wishes
Jens

Forums:

aaigner's picture

aaigner | Mon, 11/09/2015 - 20:45

Hi Jens!
To be honest I do not remember a special reason, but at least I wrote a comment in the code, so I had probably a reason for doing so. I will check the reference this week and come back to this threat.
Maybe it is just a bug.

Bests
Andreas

jenslaube | Tue, 11/10/2015 - 14:06

Hi Andreas,

thanks a lot for your reply! After going again through the reference, I can safely state that in the reference the damping was only neglected at full mobilization to enable better comparability between different rolling-friction models. The authors state several times (section 5.3, p. 274 and section 7.4, p. 279 ) that the coefficient f can be chosen differently to achieve higher viscous effects.
I guess that you implemented the model as is to avoid another coefficient to be chosen by the user.

Best wishes
Jens

aaigner's picture

aaigner | Mon, 11/23/2015 - 22:13

Hi Jens!
Thanks for your effort. You are right, I implemented it as is. Therefore, I choose f as 0.
Cheers
Andreas