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Wed, Nov 27, 11:37
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rLAMMPS lammps
fix_smd_adjust_dt.html
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<HTML>
<CENTER><A
HREF =
"http://lammps.sandia.gov"
>
LAMMPS WWW Site
</A>
-
<A
HREF =
"Manual.html"
>
LAMMPS Documentation
</A>
-
<A
HREF =
"Section_commands.html#comm"
>
LAMMPS Commands
</A>
</CENTER>
<HR>
<H3>
fix smd/adjust_dt command
</H3>
<P><B>
Syntax:
</B>
</P>
<PRE>
fix ID group-ID smd/adjust_dt arg
</PRE>
<UL><LI>
ID, group-ID are documented in
<A
HREF =
"fix.html"
>
fix
</A>
command
<LI>
smd/adjust_dt = style name of this fix command
<LI>
arg =
<I>
s_fact
</I>
<PRE>
<I>
s_fact
</I>
= safety factor
</PRE>
</UL>
<P><B>
Examples:
</B>
</P>
<PRE>
fix 1 all smd/adjust_dt 0.1
</PRE>
<P><B>
Description:
</B>
</P>
<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
<I>
s_fact
</I>
is applied to the time increment.
</P>
<P>
See
<A
HREF =
"USER/smd/SMD_LAMMPS_userguide.pdf"
>
this PDF guide
</A>
to use Smooth Mach Dynamics in LAMMPS.
</P>
<P><B>
Restart, fix_modify, output, run start/stop, minimize info:
</B>
</P>
<P>
Currently, no part of USER-SMD supports restarting nor minimization.
</P>
<P><B>
Restrictions:
</B>
</P>
<P>
This fix is part of the USER-SMD package. It is only enabled if
LAMMPS was built with that package. See the
<A
HREF =
"Section_start.html#start_3"
>
Making LAMMPS
</A>
section for more info.
</P>
<P><B>
Related commands:
</B>
</P>
<P><A
HREF =
"compute_smd_tlsph_dt.html"
>
smd/tlsph_dt
</A>
</P>
<P><B>
Default:
</B>
none
</P>
</HTML>
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