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enable fix rigid commands to add gravity to COM of rigid bodies

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This commit is contained in:
Steve Plimpton
2019-12-06 11:04:50 -07:00
parent b1668f28dd
commit 5859b18d2f
6 changed files with 146 additions and 22 deletions
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52
src/fix_gravity.cpp
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@ -37,7 +37,8 @@ enum{CONSTANT,EQUAL};
FixGravity::FixGravity(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg),
mstr(NULL), vstr(NULL), pstr(NULL), tstr(NULL), xstr(NULL), ystr(NULL), zstr(NULL)
mstr(NULL), vstr(NULL), pstr(NULL), tstr(NULL),
xstr(NULL), ystr(NULL), zstr(NULL)
{
if (narg < 5) error->all(FLERR,"Illegal fix gravity command");
@ -61,8 +62,10 @@ FixGravity::FixGravity(LAMMPS *lmp, int narg, char **arg) :
mstyle = CONSTANT;
}
int iarg;
if (strcmp(arg[4],"chute") == 0) {
if (narg != 6) error->all(FLERR,"Illegal fix gravity command");
if (narg < 6) error->all(FLERR,"Illegal fix gravity command");
style = CHUTE;
if (strstr(arg[5],"v_") == arg[5]) {
int n = strlen(&arg[5][2]) + 1;
@ -73,9 +76,10 @@ FixGravity::FixGravity(LAMMPS *lmp, int narg, char **arg) :
vert = force->numeric(FLERR,arg[5]);
vstyle = CONSTANT;
}
iarg = 6;
} else if (strcmp(arg[4],"spherical") == 0) {
if (narg != 7) error->all(FLERR,"Illegal fix gravity command");
if (narg < 7) error->all(FLERR,"Illegal fix gravity command");
style = SPHERICAL;
if (strstr(arg[5],"v_") == arg[5]) {
int n = strlen(&arg[5][2]) + 1;
@ -95,9 +99,10 @@ FixGravity::FixGravity(LAMMPS *lmp, int narg, char **arg) :
theta = force->numeric(FLERR,arg[6]);
tstyle = CONSTANT;
}
iarg = 7;
} else if (strcmp(arg[4],"vector") == 0) {
if (narg != 8) error->all(FLERR,"Illegal fix gravity command");
if (narg < 8) error->all(FLERR,"Illegal fix gravity command");
style = VECTOR;
if (strstr(arg[5],"v_") == arg[5]) {
int n = strlen(&arg[5][2]) + 1;
@ -126,9 +131,23 @@ FixGravity::FixGravity(LAMMPS *lmp, int narg, char **arg) :
zdir = force->numeric(FLERR,arg[7]);
zstyle = CONSTANT;
}
iarg = 8;
} else error->all(FLERR,"Illegal fix gravity command");
// optional keywords
disable = 0;
while (iarg < narg) {
if (strcmp(arg[iarg],"disable") == 0) {
disable = 1;
iarg++;
} else error->all(FLERR,"Illegal fix gravity command");
}
// initializations
degree2rad = MY_PI/180.0;
time_origin = update->ntimestep;
@ -266,6 +285,12 @@ void FixGravity::post_force(int /*vflag*/)
set_acceleration();
}
// just exit if application of force is disabled
if (disable) return;
// apply gravity force to each particle
double **x = atom->x;
double **f = atom->f;
double *rmass = atom->rmass;
@ -338,9 +363,9 @@ void FixGravity::set_acceleration()
}
}
xacc = magnitude*xgrav;
yacc = magnitude*ygrav;
zacc = magnitude*zgrav;
gvec[0] = xacc = magnitude*xgrav;
gvec[1] = yacc = magnitude*ygrav;
gvec[2] = zacc = magnitude*zgrav;
}
/* ----------------------------------------------------------------------
@ -357,3 +382,16 @@ double FixGravity::compute_scalar()
}
return egrav_all;
}
/* ----------------------------------------------------------------------
extract current gravity direction vector
------------------------------------------------------------------------- */
void *FixGravity::extract(const char *name, int &dim)
{
if (strcmp(name,"gvec") == 0) {
dim = 1;
return (void *) gvec;
}
return NULL;
}