forked from lijiext/lammps
73 lines
2.6 KiB
HTML
73 lines
2.6 KiB
HTML
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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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</CENTER>
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<HR>
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<H3>pair_style sph/taitwater command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style sph/taitwater
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</PRE>
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<P><B>Examples:</B>
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</P>
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<P>pair_style sph/taitwater
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pair_coeff * * 1000.0 1430.0 1.0 2.4
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</P>
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<P><B>Description:</B>
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</P>
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<P>The sph/taitwater style computes pressure forces between particles according to Tait's equation of state,
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\begin<I>equation</I>
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p = B <B>(\frac<I>\rho</I><I>\rho_0</I>)^<I>\gamma</I> - 1</B>,
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\end<I>equation</I>
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where $\gamma=7$ and $B=c_0^2 \rho_0 / \gamma$, with $\rho_0$ being the reference density and $c_0$ the reference speed of sound.
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This pair style also computes Monaghan's artificial viscosity to prevent particles from interpentrating (Monaghan1983).
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</P>
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<P>The following coefficients must be defined for each pair of atoms
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types via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples
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above.
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</P>
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<P>rho0 reference density (mass/volume units)
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c0 reference soundspeed (distance/time units)
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nu artificial viscosity (no units)
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h kernel function cutoff (distance units)
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</P>
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<HR>
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<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
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</P>
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<P>These pair styles do not support mixing. Thus, coefficients for all
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I,J pairs must be specified explicitly. Additionally, because rho0 and c0 are defined on a per-type basis,
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an I,I as well a J,J coefficients line must be specified prior to specifying an I,J interaction.
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</P>
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<P>This style does not write information to <A HREF = "restart.html">binary restart
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files</A>, so pair_style and pair_coeff commands do need
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to be specified in an input script that reads a restart file.
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</P>
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<P>These styles can only be used via the <I>pair</I> keyword of the <A HREF = "run_style.html">run_style
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respa</A> command. They do not support the <I>inner</I>,
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<I>middle</I>, <I>outer</I> keywords.
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</P>
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<P><B>Restrictions:</B>
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</P>
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<P>The <I>pair sph/taitwater</I> style is part of the "USER-SPH" package. It is
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only enabled if LAMMPS was built with that package (which it is by
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default). See the <A HREF = "Section_start.html#2_3">Making LAMMPS</A> section for
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more info.
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "pair_coeff.html">pair_coeff</A>, pair_sph/rhosum
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</P>
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<P><B>Default:</B> none
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</P>
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<P><B>(Monaghan1983)</B> J. J. Monaghan and R. A. Gingold, “Shock simulation by the particle method SPH,” Journal of Computational Physics, vol. 52, no. 2, pp. 374-389, Nov. 1983.
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</P>
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</HTML>
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