cohesion model sjkr2

Purpose

Modelling material cohesion using a modified version of the simplified Johnson-Kendall-Roberts (SJKR) cohesion model.

Syntax

cohesion sjkr2 [other model_type/model_name pairs as described here ] settings keyword values

zero or one keyword/value pairs may be appended after the keyword settings (after all models are specified)

tangential_reduce values = 'on' or 'off'
  on = tangential model does not see normal force computed by this model
  off = tangential model does see normal force computed by this model

Associated material properties

Material interaction properties

cohesionEnergyDensity ( $k$ ): cohesion energy density between the two materials [energy/length^3]

Description

This model can be used as part of pair gran and fix wall/gran

The only difference between this model and the SJKR is the way the particle-particle contact area is calculated. This model calculates the contact area as:

$A = 4 \pi \delta_n r_{eff}$

where $\delta_n$ is the overlap between two generic particles $i$ and $j$ , and $r_{eff} = r_i r_j/(r_i+r_j)$ is the effective radius.

The optional keyword tangential_reduce specifies if the tangential force model should be affected by the additional normal force exerted by this model. If set to ‘off’ (which is default), then the tangential force model will take into account the extra normal force generated by this model; hence, the tangential force model will be able to transmit a larger amount of tangential force. If set to ‘on’, then the tangential model will not take the normal force from this model into account, typically leading to a lower value of tangential force (via the Coulomb friction limit).

Restrictions

The cohesion model has been derived for the Hertzian Style, it may note be appropriate for the Hookean styles.

It is not available for atom_style superquadric

Coarse-graining information:

Using coarsegraining in combination with this command might lead to statistically different dynamics and system state. To the best knowledge of the developers, the cross-influence between this command and coarse-graining is unknown.

Default

tangential_reduce = ‘off’