fix relax/contacts command

Syntax

fix ID group-ID relax/contacts ntimesteps_relax nts keyword value

  • ID, group-ID are documented in fix command

  • relax/contacts = style name of this fix command

  • ntimesteps_relax = obligatory keyword

ntimesteps_relax nts = steps
    steps = number of time-steps during which relaxation takes place

  • zero or more force keyword/value pairs may be appended

  • keyword = region

region value = reg
  reg = region-id in which relaxation is applied

Examples

fix myId relax/contacts ntimesteps_relax 10000
fix otherId relax/contacts ntimesteps_relax 30000 region myRegion

Description

This fix allows for a smooth switching between standard and fast DEM. When the fix addforce/steadystate is enabled the contact forces between particles is normally given entirely from the steady state data. In order to smooth the transition from standard to fast (or vice versa) the present fix can be enabled.

This fix will apply a smoothing function to transition from the old to the new force computation over the course of ntimesteps_relax time steps. If the region keyword is present, this fix will only be applied to particles in a certain region.

The aim of this fix is to enable a faster transition into a smoother packing in a fastDEM simulation. For more information see also the fastDEM guide.

Restrictions

none

Coarse-graining information:

Using coarsegraining in combination with this command might lead to different dynamics or system state and thus to inconsistencies. However, the influence of this model on the global dynamics or system state might be small so in some cases the results may be valid. This has to be reviewed by a specialist on a case-by-case basis.

Default

none