69 lines
1.7 KiB
ReStructuredText
69 lines
1.7 KiB
ReStructuredText
.. index:: fix smd/adjust_dt
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fix smd/adjust_dt command
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=========================
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Syntax
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""""""
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.. code-block:: LAMMPS
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fix ID group-ID smd/adjust_dt arg
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* ID, group-ID are documented in :doc:`fix <fix>` command
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* smd/adjust_dt = style name of this fix command
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* arg = *s_fact*
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.. parsed-literal::
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*s_fact* = safety factor
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Examples
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""""""""
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.. code-block:: LAMMPS
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fix 1 all smd/adjust_dt 0.1
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Description
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"""""""""""
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The fix calculates a new stable time increment for use with the SMD
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time integrators.
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The stable time increment is based on multiple conditions. For the SPH
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pair styles, a CFL criterion (Courant, Friedrichs & Lewy, 1928) is
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evaluated, which determines the speed of sound cannot propagate
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further than a typical spacing between particles within a single time
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step to ensure no information is lost. For the contact pair styles, a
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linear analysis of the pair potential determines a stable maximum time
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step.
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This fix inquires the minimum stable time increment across all
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particles contained in the group for which this fix is defined. An
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additional safety factor *s_fact* is applied to the time increment.
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See `this PDF guide <PDF/SMD_LAMMPS_userguide.pdf>`_ to use Smooth Mach
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Dynamics in LAMMPS.
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Restart, fix_modify, output, run start/stop, minimize info
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"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
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Currently, no part of USER-SMD supports restarting nor minimization.
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Restrictions
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""""""""""""
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This fix is part of the USER-SMD package. It is only enabled if
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LAMMPS was built with that package. See the :doc:`Build package <Build_package>` doc page for more info.
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Related commands
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""""""""""""""""
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:doc:`smd/tlsph_dt <compute_smd_tlsph_dt>`
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Default
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"""""""
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none
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