ball fix command

Syntax

ball fix keyword ... <range>

Primary keywords:

spin    spin-x    spin-y    spin-z    velocity    velocity-x    velocity-y    velocity-z

Fix the specified ball velocities. As a result, ball motion is constant in the specified directions.

spin

The angular velocity is fixed.

spin-x (3D ONLY)

Fix the \(x\)-component of the angular velocity.

spin-y (3D ONLY)

Fix the \(y\)-component of the angular velocity.

spin-z (3D ONLY)

Fix the \(z\)-component of the angular velocity.

velocity

The translational velocity is fixed.

velocity-x

Fix the \(x\)-component of the translational velocity.

velocity-y

Fix the \(y\)-component of the translational velocity.

velocity-z (3D ONLY)

Fix the \(z\)-component of the translational velocity.

Usage Examples

Fix (set constant) the \(x\)-, \(y\)-, and \(z\)-velocities and spin for balls whose centroids’ \(x\)-positions lie between -3 and -1.

ball fix velocity-x velocity-y velocity-z spin-x spin-y spin-z ...
         range position-x -3 -1

from “fragment.dat” in Fragmentation Analysis during a Uniaxial Compression with Crack Tracking Using Fractures

Fix the \(z\)-velocity for all balls in the group named bottom_grip.

ball fix velocity-z range group 'bottom_grip'

from “tension.dat” in Rock Testing

Fix translational velocity for all balls whose centroids’ \(y\)-positions lie between -6 and -5.5.

ball fix vel range position-y -6 -5.5

from “load.dat” in Slip on a Fault