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fix_wall_srd.cpp
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Sun, Sep 29, 23:54

fix_wall_srd.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.
------------------------------------------------------------------------- */
#include "stdlib.h"
#include "string.h"
#include "fix_wall_srd.h"
#include "atom.h"
#include "modify.h"
#include "fix.h"
#include "domain.h"
#include "lattice.h"
#include "input.h"
#include "modify.h"
#include "update.h"
#include "variable.h"
#include "memory.h"
#include "error.h"
#include "force.h"
using namespace LAMMPS_NS;
using namespace FixConst;
enum{XLO,XHI,YLO,YHI,ZLO,ZHI};
enum{NONE,EDGE,CONSTANT,VARIABLE};
/* ---------------------------------------------------------------------- */
FixWallSRD::FixWallSRD(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg < 4) error->all(FLERR,"Illegal fix wall/srd command");
// parse args
nwall = 0;
int scaleflag = 1;
int iarg = 3;
while (iarg < narg) {
if ((strcmp(arg[iarg],"xlo") == 0) || (strcmp(arg[iarg],"xhi") == 0) ||
(strcmp(arg[iarg],"ylo") == 0) || (strcmp(arg[iarg],"yhi") == 0) ||
(strcmp(arg[iarg],"zlo") == 0) || (strcmp(arg[iarg],"zhi") == 0)) {
if (iarg+2 > narg) error->all(FLERR,"Illegal fix wall/srd command");
int newwall;
if (strcmp(arg[iarg],"xlo") == 0) newwall = XLO;
else if (strcmp(arg[iarg],"xhi") == 0) newwall = XHI;
else if (strcmp(arg[iarg],"ylo") == 0) newwall = YLO;
else if (strcmp(arg[iarg],"yhi") == 0) newwall = YHI;
else if (strcmp(arg[iarg],"zlo") == 0) newwall = ZLO;
else if (strcmp(arg[iarg],"zhi") == 0) newwall = ZHI;
for (int m = 0; m < nwall; m++)
if (newwall == wallwhich[m])
error->all(FLERR,"Wall defined twice in fix wall/srd command");
wallwhich[nwall] = newwall;
if (strcmp(arg[iarg+1],"EDGE") == 0) {
wallstyle[nwall] = EDGE;
int dim = wallwhich[nwall] / 2;
int side = wallwhich[nwall] % 2;
if (side == 0) coord0[nwall] = domain->boxlo[dim];
else coord0[nwall] = domain->boxhi[dim];
} else if (strstr(arg[iarg+1],"v_") == arg[iarg+1]) {
wallstyle[nwall] = VARIABLE;
int n = strlen(&arg[iarg+1][2]) + 1;
varstr[nwall] = new char[n];
strcpy(varstr[nwall],&arg[iarg+1][2]);
} else {
wallstyle[nwall] = CONSTANT;
coord0[nwall] = force->numeric(FLERR,arg[iarg+1]);
}
nwall++;
iarg += 2;
} else if (strcmp(arg[iarg],"units") == 0) {
if (iarg+2 > narg) error->all(FLERR,"Illegal wall/srd command");
if (strcmp(arg[iarg+1],"box") == 0) scaleflag = 0;
else if (strcmp(arg[iarg+1],"lattice") == 0) scaleflag = 1;
else error->all(FLERR,"Illegal fix wall/srd command");
iarg += 2;
} else error->all(FLERR,"Illegal fix wall/srd command");
}
// error check
if (nwall == 0) error->all(FLERR,"Illegal fix wall command");
for (int m = 0; m < nwall; m++) {
if ((wallwhich[m] == XLO || wallwhich[m] == XHI) && domain->xperiodic)
error->all(FLERR,"Cannot use fix wall/srd in periodic dimension");
if ((wallwhich[m] == YLO || wallwhich[m] == YHI) && domain->yperiodic)
error->all(FLERR,"Cannot use fix wall/srd in periodic dimension");
if ((wallwhich[m] == ZLO || wallwhich[m] == ZHI) && domain->zperiodic)
error->all(FLERR,"Cannot use fix wall/srd in periodic dimension");
}
for (int m = 0; m < nwall; m++)
if ((wallwhich[m] == ZLO || wallwhich[m] == ZHI) && domain->dimension == 2)
error->all(FLERR,"Cannot use fix wall/srd zlo/zhi for a 2d simulation");
// setup wall force array
array_flag = 1;
size_array_rows = nwall;
size_array_cols = 3;
global_freq = 1;
extarray = 1;
memory->create(fwall,nwall,3,"wall/srd:fwall");
memory->create(fwall_all,nwall,3,"wall/srd:fwall_all");
// scale coord for CONSTANT walls
int flag = 0;
for (int m = 0; m < nwall; m++)
if (wallstyle[m] == CONSTANT) flag = 1;
if (flag) {
double xscale,yscale,zscale;
if (scaleflag) {
xscale = domain->lattice->xlattice;
yscale = domain->lattice->ylattice;
zscale = domain->lattice->zlattice;
}
else xscale = yscale = zscale = 1.0;
double scale;
for (int m = 0; m < nwall; m++) {
if (wallwhich[m] < YLO) scale = xscale;
else if (wallwhich[m] < ZLO) scale = yscale;
else scale = zscale;
if (wallstyle[m] == CONSTANT) coord0[m] *= scale;
}
}
// set overlap if walls exist in multiple dimensions
int dimflag[3];
dimflag[0] = dimflag[1] = dimflag[2] = 0;
for (int m = 0; m < nwall; m++)
dimflag[wallwhich[m]/2] = 1;
if (dimflag[0] + dimflag[1] + dimflag[2] > 1) overlap = 1;
else overlap = 0;
// set varflag if any wall positions are variable
varflag = 0;
for (int m = 0; m < nwall; m++)
if (wallstyle[m] == VARIABLE) varflag = 1;
laststep = -1;
}
/* ---------------------------------------------------------------------- */
FixWallSRD::~FixWallSRD()
{
for (int m = 0; m < nwall; m++)
if (wallstyle[m] == VARIABLE) delete [] varstr[m];
memory->destroy(fwall);
memory->destroy(fwall_all);
}
/* ---------------------------------------------------------------------- */
int FixWallSRD::setmask()
{
int mask = 0;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixWallSRD::init()
{
int flag = 0;
for (int m = 0; m < modify->nfix; m++)
if (strcmp(modify->fix[m]->style,"srd") == 0) flag = 1;
if (!flag) error->all(FLERR,"Cannot use fix wall/srd without fix srd");
for (int m = 0; m < nwall; m++) {
if (wallstyle[m] != VARIABLE) continue;
varindex[m] = input->variable->find(varstr[m]);
if (varindex[m] < 0)
error->all(FLERR,"Variable name for fix wall/srd does not exist");
if (!input->variable->equalstyle(varindex[m]))
error->all(FLERR,"Variable for fix wall/srd is invalid style");
}
dt = update->dt;
}
/* ----------------------------------------------------------------------
return force component on a wall
------------------------------------------------------------------------- */
double FixWallSRD::compute_array(int i, int j)
{
// only sum across procs one time
if (force_flag == 0) {
MPI_Allreduce(&fwall[0][0],&fwall_all[0][0],3*nwall,
MPI_DOUBLE,MPI_SUM,world);
force_flag = 1;
}
return fwall_all[i][j];
}
/* ----------------------------------------------------------------------
set wall position and velocity, zero forces on walls
evaluate variable if necessary, wrap with clear/add
if flag, then being called on reneighbor, so archive wall positions
------------------------------------------------------------------------- */
void FixWallSRD::wall_params(int flag)
{
double xnew;
if (varflag) modify->clearstep_compute();
bigint ntimestep = update->ntimestep;
for (int m = 0; m < nwall; m++) {
if (wallstyle[m] == VARIABLE)
xnew = input->variable->compute_equal(varindex[m]);
else xnew = coord0[m];
if (laststep < 0) {
xwall[m] = xwalllast[m] = xnew;
vwall[m] = 0.0;
} else if (laststep < ntimestep) {
xwalllast[m] = xwall[m];
xwall[m] = xnew;
vwall[m] = (xwall[m] - xwalllast[m]) / dt;
}
fwall[m][0] = fwall[m][1] = fwall[m][2] = 0.0;
}
laststep = ntimestep;
if (varflag) modify->addstep_compute(update->ntimestep + 1);
if (flag)
for (int m = 0; m < nwall; m++)
xwallhold[m] = xwall[m];
force_flag = 0;
}

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