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fix smd/adjust_dt command
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<li><a
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"#"
>
fix smd/adjust_dt command
</a><ul>
<li><a
class=
"reference internal"
href=
"#syntax"
>
Syntax
</a></li>
<li><a
class=
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Examples
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Description
</a></li>
<li><a
class=
"reference internal"
href=
"#restart-fix-modify-output-run-start-stop-minimize-info"
>
Restart, fix_modify, output, run start/stop, minimize info
</a></li>
<li><a
class=
"reference internal"
href=
"#restrictions"
>
Restrictions
</a></li>
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Related commands
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fix smd/adjust_dt command
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<div
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<span
id=
"index-0"
></span><h1>
fix smd/adjust_dt command
</h1>
<div
class=
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id=
"syntax"
>
<h2>
Syntax
</h2>
<div
class=
"highlight-default"
><div
class=
"highlight"
><pre><span></span><span
class=
"n"
>
fix
</span>
<span
class=
"n"
>
ID
</span>
<span
class=
"n"
>
group
</span><span
class=
"o"
>
-
</span><span
class=
"n"
>
ID
</span>
<span
class=
"n"
>
smd
</span><span
class=
"o"
>
/
</span><span
class=
"n"
>
adjust_dt
</span>
<span
class=
"n"
>
arg
</span>
</pre></div>
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<li>
ID, group-ID are documented in
<a
class=
"reference internal"
href=
"fix.html"
><span
class=
"doc"
>
fix
</span></a>
command
</li>
<li>
smd/adjust_dt = style name of this fix command
</li>
<li>
arg =
<em>
s_fact
</em></li>
</ul>
<pre
class=
"literal-block"
>
<em>
s_fact
</em>
= safety factor
</pre>
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<h2>
Examples
</h2>
<div
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class=
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><pre><span></span><span
class=
"n"
>
fix
</span>
<span
class=
"mi"
>
1
</span>
<span
class=
"nb"
>
all
</span>
<span
class=
"n"
>
smd
</span><span
class=
"o"
>
/
</span><span
class=
"n"
>
adjust_dt
</span>
<span
class=
"mf"
>
0.1
</span>
</pre></div>
</div>
</div>
<div
class=
"section"
id=
"description"
>
<h2>
Description
</h2>
<p>
The fix calculates a new stable time increment for use with the SMD time integrators.
</p>
<p>
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.
</p>
<p>
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
<em>
s_fact
</em>
is applied to the time increment.
</p>
<p>
See
<a
class=
"reference external"
href=
"USER/smd/SMD_LAMMPS_userguide.pdf"
>
this PDF guide
</a>
to use Smooth Mach Dynamics in LAMMPS.
</p>
</div>
<div
class=
"section"
id=
"restart-fix-modify-output-run-start-stop-minimize-info"
>
<h2>
Restart, fix_modify, output, run start/stop, minimize info
</h2>
<p>
Currently, no part of USER-SMD supports restarting nor minimization.
</p>
</div>
<div
class=
"section"
id=
"restrictions"
>
<h2>
Restrictions
</h2>
<p>
This fix is part of the USER-SMD package. It is only enabled if
LAMMPS was built with that package. See the
<span
class=
"xref std std-ref"
>
Making LAMMPS
</span>
section for more info.
</p>
</div>
<div
class=
"section"
id=
"related-commands"
>
<h2>
Related commands
</h2>
<p><a
class=
"reference internal"
href=
"compute_smd_tlsph_dt.html"
><span
class=
"doc"
>
smd/tlsph_dt
</span></a></p>
<p><strong>
Default:
</strong>
none
</p>
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