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lammps
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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@1162 f3b2605a-c512-4ea7-a41b-209d697bcdaa

This commit is contained in:
sjplimp 2007-11-13 23:10:22 +00:00
parent f7c3c7893f
commit 67a33f24d6
2 changed files with 36 additions and 4 deletions
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37
src/fix_drag.cpp
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@ -30,6 +30,11 @@ FixDrag::FixDrag(LAMMPS *lmp, int narg, char **arg) :
{
if (narg != 8) error->all("Illegal fix drag command");
vector_flag = 1;
size_vector = 3;
scalar_vector_freq = 1;
extensive = 1;
xflag = yflag = zflag = 1;
if (strcmp(arg[3],"NULL") == 0) xflag = 0;
@ -85,8 +90,11 @@ void FixDrag::post_force(int vflag)
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
ftotal[0] = ftotal[1] = ftotal[2] = 0.0;
force_flag = 0;
double dx,dy,dz,r,prefactor;
double dx,dy,dz,r,prefactor,fx,fy,fz;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
@ -100,9 +108,15 @@ void FixDrag::post_force(int vflag)
r = sqrt(dx*dx + dy*dy + dz*dz);
if (r > delta) {
prefactor = f_mag/r;
f[i][0] -= prefactor*dx;
f[i][1] -= prefactor*dy;
f[i][2] -= prefactor*dz;
fx = prefactor*dx;
fy = prefactor*dy;
fz = prefactor*dz;
f[i][0] -= fx;
f[i][1] -= fy;
f[i][2] -= fz;
ftotal[0] -= fx;
ftotal[1] -= fy;
ftotal[2] -= fz;
}
}
}
@ -113,3 +127,18 @@ void FixDrag::post_force_respa(int vflag, int ilevel, int iloop)
{
if (ilevel == nlevels_respa-1) post_force(vflag);
}
/* ----------------------------------------------------------------------
return components of total drag force on fix group
------------------------------------------------------------------------- */
double FixDrag::compute_vector(int n)
{
// only sum across procs one time
if (force_flag == 0) {
MPI_Allreduce(ftotal,ftotal_all,3,MPI_DOUBLE,MPI_SUM,world);
force_flag = 1;
}
return ftotal_all[n];
}

3
src/fix_drag.h
View File

@ -26,6 +26,7 @@ class FixDrag : public Fix {
void setup();
void post_force(int);
void post_force_respa(int, int, int);
double compute_vector(int);
private:
double xc,yc,zc;
@ -33,6 +34,8 @@ class FixDrag : public Fix {
int xflag,yflag,zflag;
double delta;
int nlevels_respa;
double ftotal[3],ftotal_all[3];
int force_flag;
};
}