# gran tangential no_history model

## Syntax

    tangential no_history [other model_type/model_name pairs as described here ] keyword values

- zero or more keyword/value pairs may be appended to the end (after all models are specified)

    disableTangentialWhenBonded values = 'on' or 'off'
      on = if the cohesion bond model is used, then the tangential force is only added if the two particles are not bonded
      of = the normal force is always added if two particles overlap

    computeDissipatedEnergy values = 'on' or 'off'
      on = the tangential model saves the dissipated energy for each contact for the
      use in fix calculate/dissipated_energy
      of = no values are saved

LIGGGHTS(R)-PUBLIC vs. LAMMPS Info:

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

## Description

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

If this model is chose, then this “tangential overlap” spring force is NOT calculated / taken into account, i.e. k_t = 0.

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 formulas above.

When the `cohesion model bond` is used the disableTangentialWhenBonded keyword can be used. If this parameter is set to ‘on’ then the tangential model will only compute its contribution if the two neighboring particles do not have an active bond.

Coarse-graining information:

Using `coarsegraining` in combination with this command should lead to statistically equivalent dynamics in the system.

Note

`Coarsegraining` may or may not be available in LIGGGHTS(R)-PUBLIC.