mirror of https://github.com/lammps/lammps.git
150 lines
4.3 KiB
C++
150 lines
4.3 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 "stdio.h"
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#include "stdlib.h"
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#include "string.h"
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#include "fix_gravity.h"
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#include "atom.h"
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#include "update.h"
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#include "error.h"
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using namespace LAMMPS_NS;
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/* ---------------------------------------------------------------------- */
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FixGravity::FixGravity(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("Illegal fix gravity command");
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if (strcmp(arg[3],"chute") == 0) {
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if (narg != 5) error->all("Illegal fix gravity command");
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if (atom->check_style("granular") == 0)
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error->all("Must use fix gravity chute with atom style granular");
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dynamic = 0;
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granular = 1;
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phi = 0.0;
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theta = 180.0 - atof(arg[4]);
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} else if (strcmp(arg[3],"spherical") == 0) {
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if (narg != 6) error->all("Illegal fix gravity command");
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if (atom->check_style("granular") == 0)
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error->all("Must use fix gravity spherical with atom style granular");
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dynamic = 0;
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granular = 1;
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phi = atof(arg[4]);
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theta = atof(arg[5]);
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} else if (strcmp(arg[3],"gradient") == 0) {
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if (narg != 8) error->all("Illegal fix gravity command");
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if (atom->check_style("granular") == 0)
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error->all("Must use fix gravity gradient with atom style granular");
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dynamic = 1;
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granular = 1;
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phi = atof(arg[4]);
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theta = atof(arg[5]);
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phigrad = atof(arg[6]);
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thetagrad = atof(arg[7]);
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} else if (strcmp(arg[3],"vector") == 0) {
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if (narg != 8) error->all("Illegal fix gravity command");
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if (atom->check_style("granular") != 0)
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error->all("Cannot use fix gravity vector with atom style granular");
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dynamic = 0;
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granular = 0;
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magnitude = atof(arg[4]);
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xdir = atof(arg[5]);
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ydir = atof(arg[6]);
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zdir = atof(arg[7]);
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} else error->all("Illegal fix gravity command");
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double PI = 2.0 * asin(1.0);
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degree2rad = 2.0*PI / 360.0;
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time_initial = update->ntimestep;
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}
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/* ---------------------------------------------------------------------- */
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int FixGravity::setmask()
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{
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int mask = 0;
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mask |= POST_FORCE;
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return mask;
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}
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/* ---------------------------------------------------------------------- */
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void FixGravity::init()
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{
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dt = update->dt;
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if (granular) {
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xgrav = sin(degree2rad * theta) * cos(degree2rad * phi);
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ygrav = sin(degree2rad * theta) * sin(degree2rad * phi);
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zgrav = cos(degree2rad * theta);
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} else {
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double length = sqrt(xdir*xdir + ydir*ydir + zdir*zdir);
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xgrav = magnitude * xdir/length;
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ygrav = magnitude * ydir/length;
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zgrav = magnitude * zdir/length;
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}
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}
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/* ---------------------------------------------------------------------- */
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void FixGravity::setup()
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{
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post_force(1);
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}
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/* ---------------------------------------------------------------------- */
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void FixGravity::post_force(int vflag)
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{
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// update direction of gravity vector if dynamic
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if (dynamic) {
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double phi_current = degree2rad *
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(phi + (update->ntimestep-time_initial)*dt*phigrad*360.0);
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double theta_current = degree2rad *
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(theta + (update->ntimestep-time_initial)*dt*thetagrad*360.0);
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xgrav = sin(theta_current) * cos(phi_current);
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ygrav = sin(theta_current) * sin(phi_current);
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zgrav = cos(theta_current);
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}
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double **f = atom->f;
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double *rmass = atom->rmass;
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double *mass = atom->mass;
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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 massone;
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if (granular) {
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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f[i][0] += rmass[i]*xgrav;
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f[i][1] += rmass[i]*ygrav;
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f[i][2] += rmass[i]*zgrav;
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}
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} else {
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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massone = mass[type[i]];
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f[i][0] += massone*xgrav;
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f[i][1] += massone*ygrav;
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f[i][2] += massone*zgrav;
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}
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}
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}
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