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fix_wall_gran_omp.cpp
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Sun, Jul 28, 06:01

fix_wall_gran_omp.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 author: Axel Kohlmeyer (Temple U)
------------------------------------------------------------------------- */
#include <math.h>
#include "fix_wall_gran_omp.h"
#include "atom.h"
#include "memory.h"
#include "neighbor.h"
#include "update.h"
using namespace LAMMPS_NS;
using namespace FixConst;
enum{XPLANE=0,YPLANE=1,ZPLANE=2,ZCYLINDER}; // XYZ PLANE need to be 0,1,2
enum{HOOKE,HOOKE_HISTORY,HERTZ_HISTORY};
#define BIG 1.0e20
/* ---------------------------------------------------------------------- */
FixWallGranOMP::FixWallGranOMP(LAMMPS *lmp, int narg, char **arg) :
FixWallGran(lmp, narg, arg) { }
/* ---------------------------------------------------------------------- */
void FixWallGranOMP::post_force(int vflag)
{
double vwall[3];
// if just reneighbored:
// update rigid body masses for owned atoms if using FixRigid
// body[i] = which body atom I is in, -1 if none
// mass_body = mass of each rigid body
if (neighbor->ago == 0 && fix_rigid) {
int tmp;
const int * const body = (const int * const) fix_rigid->extract("body",tmp);
double *mass_body = (double *) fix_rigid->extract("masstotal",tmp);
if (atom->nmax > nmax) {
memory->destroy(mass_rigid);
nmax = atom->nmax;
memory->create(mass_rigid,nmax,"wall/gran:mass_rigid");
}
const int nlocal = atom->nlocal;
for (int i = 0; i < nlocal; i++) {
if (body[i] >= 0) mass_rigid[i] = mass_body[body[i]];
else mass_rigid[i] = 0.0;
}
}
// set position of wall to initial settings and velocity to 0.0
// if wiggle or shear, set wall position and velocity accordingly
double wlo = lo;
double whi = hi;
vwall[0] = vwall[1] = vwall[2] = 0.0;
if (wiggle) {
double arg = omega * (update->ntimestep - time_origin) * dt;
if (wallstyle == axis) {
wlo = lo + amplitude - amplitude*cos(arg);
whi = hi + amplitude - amplitude*cos(arg);
}
vwall[axis] = amplitude*omega*sin(arg);
} else if (wshear) vwall[axis] = vshear;
// loop over all my atoms
// rsq = distance from wall
// dx,dy,dz = signed distance from wall
// for rotating cylinder, reset vwall based on particle position
// skip atom if not close enough to wall
// if wall was set to NULL, it's skipped since lo/hi are infinity
// compute force and torque on atom if close enough to wall
// via wall potential matched to pair potential
// set shear if pair potential stores history
double * const * const x = atom->x;
double * const * const v = atom->v;
double * const * const f = atom->f;
double * const * const omega = atom->omega;
double * const * const torque = atom->torque;
double * const radius = atom->radius;
double * const rmass = atom->rmass;
const int * const mask = atom->mask;
const int nlocal = atom->nlocal;
shearupdate = (update->setupflag) ? 0 : 1;
int i;
#if defined(_OPENMP)
#pragma omp parallel for private(i) default(none) firstprivate(vwall,wlo,whi)
#endif
for (i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
double dx,dy,dz,del1,del2,delxy,delr,rsq;
dx = dy = dz = 0.0;
if (wallstyle == XPLANE) {
del1 = x[i][0] - wlo;
del2 = whi - x[i][0];
if (del1 < del2) dx = del1;
else dx = -del2;
} else if (wallstyle == YPLANE) {
del1 = x[i][1] - wlo;
del2 = whi - x[i][1];
if (del1 < del2) dy = del1;
else dy = -del2;
} else if (wallstyle == ZPLANE) {
del1 = x[i][2] - wlo;
del2 = whi - x[i][2];
if (del1 < del2) dz = del1;
else dz = -del2;
} else if (wallstyle == ZCYLINDER) {
delxy = sqrt(x[i][0]*x[i][0] + x[i][1]*x[i][1]);
delr = cylradius - delxy;
if (delr > radius[i]) dz = cylradius;
else {
dx = -delr/delxy * x[i][0];
dy = -delr/delxy * x[i][1];
if (wshear && axis != 2) {
vwall[0] = vshear * x[i][1]/delxy;
vwall[1] = -vshear * x[i][0]/delxy;
vwall[2] = 0.0;
}
}
}
rsq = dx*dx + dy*dy + dz*dz;
if (rsq > radius[i]*radius[i]) {
if (pairstyle != HOOKE) {
shear[i][0] = 0.0;
shear[i][1] = 0.0;
shear[i][2] = 0.0;
}
} else {
// meff = effective mass of sphere
// if I is part of rigid body, use body mass
double meff = rmass[i];
if (fix_rigid && mass_rigid[i] > 0.0) meff = mass_rigid[i];
// inovke sphere/wall interaction
if (pairstyle == HOOKE)
hooke(rsq,dx,dy,dz,vwall,v[i],f[i],omega[i],torque[i],
radius[i],meff);
else if (pairstyle == HOOKE_HISTORY)
hooke_history(rsq,dx,dy,dz,vwall,v[i],f[i],omega[i],torque[i],
radius[i],meff,shear[i]);
else if (pairstyle == HERTZ_HISTORY)
hertz_history(rsq,dx,dy,dz,vwall,v[i],f[i],omega[i],torque[i],
radius[i],meff,shear[i]);
}
}
}
}
/* ---------------------------------------------------------------------- */
void FixWallGranOMP::post_force_respa(int vflag, int ilevel, int iloop)
{
if (ilevel == nlevels_respa-1) post_force(vflag);
}

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