forked from lijiext/lammps
137 lines
3.6 KiB
C++
137 lines
3.6 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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http://lammps.sandia.gov, Sandia National Laboratories
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Steve Plimpton, sjplimp@sandia.gov
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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 "math.h"
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#include "stdlib.h"
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#include "string.h"
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#include "fix_viscous.h"
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#include "atom.h"
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#include "update.h"
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#include "respa.h"
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#include "error.h"
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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) :
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Fix(lmp, narg, arg)
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{
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if (narg < 4) error->all(FLERR,"Illegal fix viscous command");
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double gamma_one = atof(arg[3]);
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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 = atoi(arg[iarg+1]);
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double scale = atof(arg[iarg+2]);
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if (itype <= 0 || itype > atom->ntypes)
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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 error->all(FLERR,"Illegal fix viscous command");
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}
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}
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/* ---------------------------------------------------------------------- */
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FixViscous::~FixViscous()
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{
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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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if (strstr(update->integrate_style,"respa"))
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nlevels_respa = ((Respa *) update->integrate)->nlevels;
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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 (strstr(update->integrate_style,"verlet"))
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post_force(vflag);
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else {
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((Respa *) update->integrate)->copy_flevel_f(nlevels_respa-1);
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post_force_respa(vflag,nlevels_respa-1,0);
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((Respa *) update->integrate)->copy_f_flevel(nlevels_respa-1);
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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 == nlevels_respa-1) 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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