particle_shape command

Purpose

Command for the defining one or more particle shapes.

Note

This command is supported by Aspherix GPU.

Syntax

particle_shape style keyword value

The following styles are available: sphere, multisphere, fiber, bonded, superquadric, convex, concave or mixed

List of available keywords:

Keywords	Description
shapes	available and obligatory for mixed, list of two or more shapes (sphere`, multisphere, fiber, bonded, superquadric, convex or concave)
use_advanced_models	yes or no; determines whether or not the advanced models are used for multispheres and concave particles default: no
magnetic	yes or no; determines whether or not a dipole moment is attached to each particle (spherical particles only) default: no
charged	yes or no; determines whether or not a particle can have charge (spherical particles only).

Examples

particle_shape sphere
particle_shape mixed shapes {sphere, multisphere}
particle_shape multisphere use_advanced_models yes
particle_shape sphere magnetic yes

Description

This command is used to define the particle shape of the bulk material used in the simulation. It ensures that the correct surface model is used for handling particle-particle and particle-wall collisions. The shapes defined by this command can used to define a particle template.

Note

For any type of bonded particles, choose particle shape fiber

The use_advanced_models keyword determines whether or not the multisphere and concave particles use their respective advanced models (see the commands multisphere/advanced and concave/advanced which are employed in the background). For all other particle shapes this option will be ignored.

This table summarizes all supported (✓) and unsupported (—) combinations of particle shapes for particle_shape mixed:

	sphere	multisphere	superquadric	fiber	bonded	convex	concave	fragments
sphere	✓	✓	✓	✓	✓	✓	✓	✓
multisphere	✓	✓	—	—	—	—	—	—
superquadric	✓	—	✓	—	—	—	—	—
fiber	✓	—	—	✓	—	—	—	—
bonded	✓	—	—	—	✓	—	—	—
convex	✓	—	—	—	—	✓	✓	—
concave	✓	—	—	—	—	✓	✓	—
fragments	✓	—	—	—	—	—	—	✓

If the magnetic keyword is set to yes a dipole moment is attached to each particle. This can interact with either the addforce/magnetic command or the lj/cut/dipole/cut pair style. If the charged keyword is set to yes, then each particle carries a charge. This is necessary for the enable_electric_field command. Both options are not available for nonspherical particles.

If particle_shape concave is set but the geometry of a convex body is provided, the particle shape will be changed to convex automatically.

Restrictions

The shapes superquadric and convex/concave cannot be used together in the list specified by the keyword shapes. When using a restart file, it is (in general) not possible to modify the previously defined particle_shape.

Related commands

atom_style, particle_template