forked from lijiext/lammps
109 lines
3.5 KiB
Plaintext
109 lines
3.5 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Commands_all.html)
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:line
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pair_style sdpd/taitwater/isothermal command :h3
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[Syntax:]
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pair_style sdpd/taitwater/isothermal temperature viscosity seed
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:pre
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temperature = temperature of the fluid (temperature units)
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viscosity = dynamic viscosity of the fluid (mass*distance/time units)
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seed = random number generator seed (positive integer, optional) :ul
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[Examples:]
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pair_style sdpd/taitwater/isothermal 300. 1. 28681
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pair_coeff * * 1000.0 1430.0 2.4 :pre
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[Description:]
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The sdpd/taitwater/isothermal style computes forces between mesoscopic
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particles according to the Smoothed Dissipative Particle Dynamics model
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described in this paper by "(Espanol and Revenga)"_#Espanol_Revenga under
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the following assumptions:
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:olb
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The temperature is constant and uniform. :l
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The shear viscosity is constant and uniform. :l
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The volume viscosity is negligible before the shear viscosity. :l
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The Boltzmann constant is negligible before the heat capacity of a
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single mesoscopic particle of fluid. :ole,l
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The third assumption is true for water in nearly incompressible flows.
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The fourth holds true for water for any reasonable size one can
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imagine for a mesoscopic particle.
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The pressure forces between particles will be computed according to
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Tait's equation of state:
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:c,image(Eqs/pair_sph_tait.jpg)
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where gamma = 7 and B = c_0^2 rho_0 / gamma, with rho_0 being the
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reference density and c_0 the reference speed of sound.
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The laminar viscosity and the random forces will be computed according
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to formulas described in "(Espanol and Revenga)"_#Espanol_Revenga.
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IMPORTANT NOTE: Similar to "brownian"_pair_brownian.html and
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"dpd"_pair_dpd.html styles, the "newton"_newton.html setting for
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pairwise interactions needs to be on when running LAMMPS in parallel
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if you want to ensure linear momentum conservation. Otherwise random
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forces generated for pairs straddling processor boundary will not be
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equal and opposite.
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NOTE: The actual random seed used will be a mix of what you specify
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and other parameters like the MPI ranks. This is to ensure that
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different MPI tasks have distinct seeds.
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The following coefficients must be defined for each pair of atoms
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types via the "pair_coeff"_pair_coeff.html command as in the examples
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above.
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rho0 reference density (mass/volume units)
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c0 reference soundspeed (distance/time units)
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h kernel function cutoff (distance units) :ul
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:line
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[Mixing, shift, table, tail correction, restart, rRESPA info]:
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This style does not support mixing. Thus, coefficients for all
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I,J pairs must be specified explicitly.
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This style does not support the "pair_modify"_pair_modify.html
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shift, table, and tail options.
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This style does not write information to "binary restart
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files"_restart.html. Thus, you need to re-specify the pair_style and
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pair_coeff commands in an input script that reads a restart file.
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This style can only be used via the {pair} keyword of the "run_style
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respa"_run_style.html command. It does not support the {inner},
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{middle}, {outer} keywords.
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[Restrictions:]
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This pair style is part of the USER-SDPD package. It is only enabled
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if LAMMPS was built with that package. See the "Build
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package"_Build_package.html doc page for more info.
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[Related commands:]
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"pair coeff"_pair_coeff.html, "pair sph/rhosum"_pair_sph_rhosum.html
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[Default:]
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The default seed is 0 (before mixing).
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:line
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:link(Espanol_Revenga)
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[(Espanol and Revenga)] Espanol, Revenga, Physical Review E, 67, 026705 (2003).
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