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<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>
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<H3>pair_style smd/ulsph command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>pair_style smd/ulsph args
</PRE>
<LI>these keywords must be given
<P>keyword = <I>*DENSITY_SUMMATION</I> or <I>*DENSITY_CONTINUITY</I> and <I>*VELOCITY_GRADIENT</I> or <I>*NO_VELOCITY_GRADIENT</I> and <I>*GRADIENT_CORRECTION</I> or <I>*NO_GRADIENT_CORRECTION</I>
</P>
<P><B>Examples:</B>
</P>
<P>pair_style smd/ulsph *DENSITY_CONTINUITY *VELOCITY_GRADIENT *NO_GRADIENT_CORRECTION
</P>
<P><B>Description:</B>
</P>
<P>The <I>smd/ulsph</I> style computes particle interactions according to continuum mechanics constitutive laws and an updated Lagrangian Smooth-Particle Hydrodynamics algorithm.
</P>
<P>This pair style is invoked similar to the following command:
</P>
<PRE>pair_style smd/ulsph *DENSITY_CONTINUITY *VELOCITY_GRADIENT *NO_GRADIENT_CORRECTION
pair_coeff i j *COMMON rho0 c0 Q1 Cp hg &
*END
</PRE>
<P>Here, <I>i</I> and <I>j</I> denote the <I>LAMMPS</I> particle types for which this pair style is
defined. Note that <I>i</I> and <I>j</I> can be different, i.e., <I>ulsph</I> cross interactions
between different particle types are allowed. However, <I>i</I>--<I>i</I> respectively <I>j</I>--<I>j</I> pair_coeff lines have to preceed a cross interaction.
In contrast to the usual <I>LAMMPS</I> <I>pair coeff</I> definitions, which are given solely a
number of floats and integers, the <I>ulsph</I> <I>pair coeff</I> definition is organised using
keywords. These keywords mark the beginning of different sets of parameters for particle properties,
material constitutive models, and damage models. The <I>pair coeff</I> line must be terminated with
the <I>*END</I> keyword. The use the line continuation operator <I>&</I> is recommended. A typical
invocation of the <I>ulsph</I> for a solid body would consist of an equation of state for computing
the pressure (the diagonal components of the stress tensor), and a material model to compute shear
stresses (the off-diagonal components of the stress tensor).
</P>
<P>Note that the use of *GRADIENT_CORRECTION can lead to severe numerical instabilities. For a general fluid simulation, *NO_GRADIENT_CORRECTION is recommended.
</P>
<P>Please see the <A HREF = "USER/smd/SMD_LAMMPS_userguide.pdf">SMD user guide</A> for a complete listing of the possible keywords and material models.
</P>
<HR>
<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
</P>
<P>No mixing is performed automatically.
Currently, no part of USER-SMD supports restarting nor minimization.
rRESPA does not apply to this pair style.
</P>
<HR>
<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 = "pair_coeff.html">pair_coeff</A>
</P>
<P><B>Default:</B> none
</P>
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