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fix_lb_viscous.cpp
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Sat, Jun 22, 13:32

fix_lb_viscous.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing authors: Frances Mackay, Santtu Ollila, Colin Denniston (UWO)
------------------------------------------------------------------------- */
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "fix_lb_viscous.h"
#include "atom.h"
#include "update.h"
#include "respa.h"
#include "error.h"
#include "fix_lb_fluid.h"
#include "modify.h"
#include "group.h"
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixLbViscous::FixLbViscous(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg < 3) error->all(FLERR,"Illegal fix lb/viscous command");
int groupbit_lb_fluid = 0;
for(int ifix=0; ifix<modify->nfix; ifix++)
if(strcmp(modify->fix[ifix]->style,"lb/fluid")==0){
fix_lb_fluid = (FixLbFluid *)modify->fix[ifix];
groupbit_lb_fluid = group->bitmask[modify->fix[ifix]->igroup];
}
if(groupbit_lb_fluid == 0)
error->all(FLERR,"the lb/fluid fix must also be used if using the lb/viscous fix");
int *mask = atom->mask;
int nlocal = atom->nlocal;
for(int j=0; j<nlocal; j++){
if((mask[j] & groupbit) && !(mask[j] & groupbit_lb_fluid))
error->one(FLERR,"to apply a fluid force onto an atom, the lb/fluid fix must be used for that atom.");
}
}
/* ---------------------------------------------------------------------- */
FixLbViscous::~FixLbViscous()
{
}
/* ---------------------------------------------------------------------- */
int FixLbViscous::setmask()
{
int mask = 0;
mask |= POST_FORCE;
mask |= POST_FORCE_RESPA;
mask |= MIN_POST_FORCE;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixLbViscous::init()
{
if (strcmp(update->integrate_style,"respa") == 0)
nlevels_respa = ((Respa *) update->integrate)->nlevels;
}
/* ---------------------------------------------------------------------- */
void FixLbViscous::setup(int vflag)
{
if (strstr(update->integrate_style,"verlet") != NULL)
post_force(vflag);
else {
((Respa *) update->integrate)->copy_flevel_f(nlevels_respa-1);
post_force_respa(vflag,nlevels_respa-1,0);
((Respa *) update->integrate)->copy_f_flevel(nlevels_respa-1);
}
}
/* ---------------------------------------------------------------------- */
void FixLbViscous::min_setup(int vflag)
{
post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixLbViscous::post_force(int vflag)
{
// apply drag force to atoms in group
// direction is opposed to velocity vector
// magnitude depends on atom type
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
double **hydroF = fix_lb_fluid->hydroF;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
f[i][0] += hydroF[i][0];
f[i][1] += hydroF[i][1];
f[i][2] += hydroF[i][2];
}
}
/* ---------------------------------------------------------------------- */
void FixLbViscous::post_force_respa(int vflag, int ilevel, int iloop)
{
if (ilevel == nlevels_respa-1) post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixLbViscous::min_post_force(int vflag)
{
post_force(vflag);
}

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