147 lines
4.0 KiB
C++
147 lines
4.0 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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https://www.lammps.org/, Sandia National Laboratories
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LAMMPS development team: developers@lammps.org
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Copyright (2003) Sandia Corporation. Under the terms of Contract
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DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
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certain rights in this software. This software is distributed under
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the GNU General Public License.
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See the README file in the top-level LAMMPS directory.
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------------------------------------------------------------------------- */
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#include "fix_viscous.h"
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#include "atom.h"
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#include "error.h"
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#include "respa.h"
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#include "update.h"
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#include <cstring>
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using namespace LAMMPS_NS;
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using namespace FixConst;
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/* ---------------------------------------------------------------------- */
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FixViscous::FixViscous(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg), gamma(nullptr)
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{
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dynamic_group_allow = 1;
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if (narg < 4) error->all(FLERR, "Illegal fix viscous command");
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double gamma_one = utils::numeric(FLERR, arg[3], false, lmp);
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gamma = new double[atom->ntypes + 1];
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for (int i = 1; i <= atom->ntypes; i++) gamma[i] = gamma_one;
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// optional args
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int iarg = 4;
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while (iarg < narg) {
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if (strcmp(arg[iarg], "scale") == 0) {
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if (iarg + 3 > narg) error->all(FLERR, "Illegal fix viscous command");
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int itype = utils::inumeric(FLERR, arg[iarg + 1], false, lmp);
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double scale = utils::numeric(FLERR, arg[iarg + 2], false, lmp);
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if (itype <= 0 || itype > atom->ntypes) error->all(FLERR, "Illegal fix viscous command");
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gamma[itype] = gamma_one * scale;
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iarg += 3;
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} else
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error->all(FLERR, "Illegal fix viscous command");
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}
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respa_level_support = 1;
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ilevel_respa = 0;
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}
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/* ---------------------------------------------------------------------- */
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FixViscous::~FixViscous()
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{
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if (copymode) return;
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delete[] gamma;
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}
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/* ---------------------------------------------------------------------- */
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int FixViscous::setmask()
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{
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int mask = 0;
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mask |= POST_FORCE;
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mask |= POST_FORCE_RESPA;
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mask |= MIN_POST_FORCE;
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return mask;
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}
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/* ---------------------------------------------------------------------- */
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void FixViscous::init()
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{
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int max_respa = 0;
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if (utils::strmatch(update->integrate_style, "^respa")) {
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ilevel_respa = max_respa = (dynamic_cast<Respa *>(update->integrate))->nlevels - 1;
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if (respa_level >= 0) ilevel_respa = MIN(respa_level, max_respa);
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixViscous::setup(int vflag)
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{
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if (utils::strmatch(update->integrate_style, "^verlet"))
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post_force(vflag);
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else {
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(dynamic_cast<Respa *>(update->integrate))->copy_flevel_f(ilevel_respa);
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post_force_respa(vflag, ilevel_respa, 0);
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(dynamic_cast<Respa *>(update->integrate))->copy_f_flevel(ilevel_respa);
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixViscous::min_setup(int vflag)
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{
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post_force(vflag);
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}
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/* ---------------------------------------------------------------------- */
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void FixViscous::post_force(int /*vflag*/)
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{
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// apply drag force to atoms in group
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// direction is opposed to velocity vector
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// magnitude depends on atom type
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double **v = atom->v;
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double **f = atom->f;
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int *mask = atom->mask;
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int *type = atom->type;
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int nlocal = atom->nlocal;
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double drag;
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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drag = gamma[type[i]];
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f[i][0] -= drag * v[i][0];
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f[i][1] -= drag * v[i][1];
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f[i][2] -= drag * v[i][2];
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixViscous::post_force_respa(int vflag, int ilevel, int /*iloop*/)
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{
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if (ilevel == ilevel_respa) post_force(vflag);
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}
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/* ---------------------------------------------------------------------- */
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void FixViscous::min_post_force(int vflag)
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{
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post_force(vflag);
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}
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