Documentation of contact formulation?

Submitted by Marco on Thu, 02/28/2013 - 13:37

Hi all,
I am currently doing a survey of contact laws implementation for granular materials. I have been reading LIGGGHTS manual and some workshop material available online, but for the moment I fail to find the equation of the "tangential component of velocity" at contacts.
It may sound a dumb question, but there are actually many possible definitions of this velocity. Any pointer to this equation in LIGGGHTS would be welcome. Thanks!

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ckloss's picture

ckloss | Mon, 03/04/2013 - 14:59

Hi Marco,

>>It may sound a dumb question, but there are actually many possible definitions of this velocity
no, the question is not dumb! There are really many ways to do it. The current implementation is a simple zero-order rotation of the shear vector (no rotation matrix or the like), Coulomb's law is applied using both spring and damper part of the force, and energy loss in the tangential part comes from either sliding or damping.

If you wanna know the details check out pair_gran_hooke_history.cpp. At the moment there is no written doc for it

Cheers
Christoph