gran cohesion sjkr¶

Syntax¶

cohesion sjkr

LIGGGHTS vs. LAMMPS Info:

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

Description¶

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

The simplified JKR - Johnson-Kendall-Roberts (SJKR) model adds an additional normal force contribution. If two particle are in contact, it adds an additional normal force tending to maintain the contact, which writes

F = k A,

where A is the particle contact area and k is the cohesion energy density in J/m3. For sjkr, the sphere-sphere contact area is calculated as (http://mathworld.wolfram.com/Sphere-SphereIntersection.html)

A = Pi/4 * ((dist-Ri-Rj)*(dist+Ri-Rj)*(dist-Ri+Rj)*(dist+Ri+Rj) )/(dist*dist)

where dist is the distance between the particle centers.

If you are using the SJKR model, you must also define the cohesion energy density:

fix id all property/global cohesionEnergyDensity peratomtypepair n_atomtypes value_11 value_12 .. value_21 value_22 .. .
    (value_ij=value for the cohesion energy density (in Energy/Length3 units) between atom type i and j; n_atomtypes is the number of atom types you want to use in your simulation)

Restrictions¶

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