"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

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fix smd/adjust_dt command :h3

[Syntax:]

fix ID group-ID smd/adjust_dt arg :pre

ID, group-ID are documented in "fix"_fix.html command :ulb,l
smd/adjust_dt = style name of this fix command :l
arg = {s_fact} :l
  {s_fact} = safety factor  :pre

:ule

[Examples:]

fix 1 all smd/adjust_dt 0.1 :pre

[Description:]

The fix calculates a new stable time increment for use with the SMD time integrators.

The stable time increment is based on multiple conditions. For the SPH pair styles, a
CFL criterion (Courant, Friedrichs & Lewy, 1928) is evaluated, which determines the speed of
sound cannot propagate further than a typical spacing between particles within a single time step to ensure
no information is lost. For the contact pair styles, a linear analysis of the pair potential determines a
stable maximum time step.

This fix inquires the minimum stable time increment across all particles contained in the group for which this
fix is defined. An additional safety factor {s_fact} is applied to the time increment.

See "this PDF guide"_PDF/SMD_LAMMPS_userguide.pdf to use Smooth Mach Dynamics in LAMMPS.

[Restart, fix_modify, output, run start/stop, minimize info:]

Currently, no part of USER-SMD supports restarting nor minimization.

[Restrictions:]

This fix is part of the USER-SMD package.  It is only enabled if
LAMMPS was built with that package. See the "Making LAMMPS"_Section_start.html#start_3
section for more info.

[Related commands:]

"smd/tlsph_dt"_compute_smd_tlsph_dt.html

[Default:] none
