gran tangential incremental_history¶

Syntax¶

tangential incremental_history

LIGGGHTS vs. LAMMPS Info:

This part of pair gran and fix wall/gran is not available in LAMMPS.

Description¶

This granular model is based on the general description of granular force interaction as described in pair gran.

The spring part of the tangential force (k_t) is a “history” effect that accounts for the tangential displacement (“tangential overlap”) between the particles for the duration of the time they are in contact.

If this model is chosen, then this “tangential overlap” spring force is actually calculated / taken into account. The coefficient of friction cof is the upper limit of the tangential force through the Coulomb criterion Ft = cof*Fn, where Ft and Fn are the tangential spring and normal force components in the contact force model.

Note that opposed to the history model which calculates the tangential force in an integral way, the incremental_history model computes the tangential force in an incremental way.

More precisely, in the history model the tangential overlap gets updated each time step by projecting the tangential overlap accumulated so far into the current tangential plane and adding the current increment of the tangential overlap. This overlap is used in combination with the current tangential spring stiffness to calculate the current tangential force.

The incremental_history model on the other hand updates the tangential force each time step by projecting the tangential force accumulated so far into the current tangential plane. The current increment of the tangential overlap is used in combination with the current tangential spring stiffness to calculate the current increment of the tangential force.

For a detailed discussion see Thornton et al. 2011 and Thornton et al. 2013

(Thornton et al., 2011) “An investigation of the comparative behaviour of alternative contact force models during elastic collisions”, C. Thornton, S.J. Cummins, P.W. Cleary, Powder Technology, 210 (3), pp. 189-197 (2011).

(Thornton et al., 2013) “An investigation of the comparative behaviour of alternative contact force models during inelastic collisions”, C. Thornton, S.J. Cummins, P.W. Cleary, Powder Technology, 233, pp. 30-46 (2013).