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lammps/doc/_sources/fix_smd_adjust_dt.txt
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fix_smd_adjust_dt.txt
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.. index:: fix smd/adjust_dt
fix smd/adjust_dt command
=========================
Syntax
""""""
.. parsed-literal::
fix ID group-ID smd/adjust_dt arg
* ID, group-ID are documented in :doc:`fix <fix>` command
* smd/adjust_dt = style name of this fix command
* arg = *s_fact*
.. parsed-literal::
*s_fact* = safety factor
Examples
""""""""
.. parsed-literal::
fix 1 all smd/adjust_dt 0.1
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 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 <USER/smd/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 :ref:`Making LAMMPS <start_3>`
section for more info.
Related commands
""""""""""""""""
:doc:`smd/tlsph_dt <compute_smd_tlsph_dt>`
**Default:** none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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