# wall tolerance command

Syntax

wall tolerance keyword ...

Primary keywords:

Set contact detection tolerances. The size of the extent with which a facet is inserted into the cell space is the minimum extent size plus twice the sum of the following quantities: 1) the maximum interaction distance; 2) the constant contact-detection tolerance (constant - default 0); 3) the maximum length of the minimum extent in all directions multiplied by the extent tolerance (extent - default $$\frac{1}{32}$$); 4) the maximum component of translational velocity multiplied by the velocity tolerance (velocity - default 0). The facet will be remapped into the cell space whenever it has translated cumulatively in any direction by this sum from the last time it was mapped into the cell space. Contacts can be created whenever the expanded extents of any pieces (i.e., balls, clump pebbles, or facets) overlap, but contacts cannot exist between facets. See the description of the cycle operations “30.0 - Update Spatial Searching Data Structures” and “35.0 - Create/delete Contacts” for more details.

Note

Directly after the model has been restored, one must call a clean (i.e., model clean) prior to modifying the extent tolerances.

automatic b

Change the automatic tolerance computation mode (on by default). If wall facets have velocity, those facets may be controlling the timestep due to the requirement of frequent remapping in the cellspace to ensure contacts are detected appropriately. In many situations few facets may be moving. Instead, the wall facet controlling the timestep is determined when b = true and the velocity contact-detection tolerance set so that the timestep is not reduced from the last stable timestep.

constant f <range>

Assign the constant contact-detection tolerance. This is assigned on a per-facet basis.

extent f

Assign the extent contact-detection tolerance. This is a global setting for all facets.

velocity f

Assign the velocity contact-detection tolerance. This is a global setting for all facets.