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lammps/src/FLD/pair_lubricate_poly.cpp
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pair_lubricate_poly.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 authors: Randy Schunk (SNL)
Amit Kumar and Michael Bybee (UIUC)
Dave Heine (Corning), polydispersity
------------------------------------------------------------------------- */
#include "math.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "pair_lubricate_poly.h"
#include "atom.h"
#include "atom_vec.h"
#include "comm.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "domain.h"
#include "update.h"
#include "modify.h"
#include "fix.h"
#include "fix_deform.h"
#include "memory.h"
#include "random_mars.h"
#include "math_const.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace MathConst;
// same as fix_deform.cpp
enum{NO_REMAP,X_REMAP,V_REMAP};
/* ---------------------------------------------------------------------- */
PairLubricatePoly::PairLubricatePoly(LAMMPS *lmp) : PairLubricate(lmp)
{
no_virial_fdotr_compute = 1;
}
/* ---------------------------------------------------------------------- */
void PairLubricatePoly::compute(int eflag, int vflag)
{
int i,j,ii,jj,inum,jnum,itype,jtype;
double xtmp,ytmp,ztmp,delx,dely,delz,fpair,fx,fy,fz,tx,ty,tz;
double rsq,r,h_sep,h_sepj,beta0,beta1,betaj,betaj1,radi,radj,tfmag;
double vr1,vr2,vr3,vnnr,vn1,vn2,vn3;
double vt1,vt2,vt3,wt1,wt2,wt3,wdotn;
double inertia,inv_inertia,vRS0;
double vi[3],vj[3],wi[3],wj[3],xl[3],jl[3];
double a_sq,a_sh,a_pu,Fbmag,del,delmin,eta;
int *ilist,*jlist,*numneigh,**firstneigh;
double lamda[3],vstream[3];
double vxmu2f = force->vxmu2f;
if (eflag || vflag) ev_setup(eflag,vflag);
else evflag = vflag_fdotr = 0;
double **x = atom->x;
double **v = atom->v;
double **f = atom->f;
double **omega = atom->omega;
double **angmom = atom->angmom;
double **torque = atom->torque;
double *radius = atom->radius;
double *mass = atom->mass;
double *rmass = atom->rmass;
int *type = atom->type;
int nlocal = atom->nlocal;
int newton_pair = force->newton_pair;
int overlaps = 0;
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
// subtract streaming component of velocity, omega, angmom
// assume fluid streaming velocity = box deformation rate
// vstream = (ux,uy,uz)
// ux = h_rate[0]*x + h_rate[5]*y + h_rate[4]*z
// uy = h_rate[1]*y + h_rate[3]*z
// uz = h_rate[2]*z
// omega_new = omega - curl(vstream)/2
// angmom_new = angmom - I*curl(vstream)/2
// Ef = (grad(vstream) + (grad(vstream))^T) / 2
if (shearing) {
double *h_rate = domain->h_rate;
double *h_ratelo = domain->h_ratelo;
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
itype = type[i];
radi = radius[i];
domain->x2lamda(x[i],lamda);
vstream[0] = h_rate[0]*lamda[0] + h_rate[5]*lamda[1] +
h_rate[4]*lamda[2] + h_ratelo[0];
vstream[1] = h_rate[1]*lamda[1] + h_rate[3]*lamda[2] + h_ratelo[1];
vstream[2] = h_rate[2]*lamda[2] + h_ratelo[2];
v[i][0] -= vstream[0];
v[i][1] -= vstream[1];
v[i][2] -= vstream[2];
omega[i][0] += 0.5*h_rate[3];
omega[i][1] -= 0.5*h_rate[4];
omega[i][2] += 0.5*h_rate[5];
}
// set Ef from h_rate in strain units
Ef[0][0] = h_rate[0]/domain->xprd;
Ef[1][1] = h_rate[1]/domain->yprd;
Ef[2][2] = h_rate[2]/domain->zprd;
Ef[0][1] = Ef[1][0] = 0.5 * h_rate[5]/domain->yprd;
Ef[0][2] = Ef[2][0] = 0.5 * h_rate[4]/domain->zprd;
Ef[1][2] = Ef[2][1] = 0.5 * h_rate[3]/domain->zprd;
// copy updated omega to the ghost particles
// no need to do this if not shearing since comm->ghost_velocity is set
comm->forward_comm_pair(this);
}
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
itype = type[i];
jlist = firstneigh[i];
jnum = numneigh[i];
radi = radius[i];
// angular velocity
wi[0] = omega[i][0];
wi[1] = omega[i][1];
wi[2] = omega[i][2];
// FLD contribution to force and torque due to isotropic terms
// FLD contribution to stress from isotropic RS0
if (flagfld) {
f[i][0] -= vxmu2f*R0*radi*v[i][0];
f[i][1] -= vxmu2f*R0*radi*v[i][1];
f[i][2] -= vxmu2f*R0*radi*v[i][2];
torque[i][0] -= vxmu2f*RT0*pow(radi,3)*wi[0];
torque[i][1] -= vxmu2f*RT0*pow(radi,3)*wi[1];
torque[i][2] -= vxmu2f*RT0*pow(radi,3)*wi[2];
if (shearing && vflag_either) {
vRS0 = -vxmu2f * RS0*pow(radi,3);
v_tally_tensor(i,i,nlocal,newton_pair,
vRS0*Ef[0][0],vRS0*Ef[1][1],vRS0*Ef[2][2],
vRS0*Ef[0][1],vRS0*Ef[0][2],vRS0*Ef[1][2]);
}
}
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
delx = xtmp - x[j][0];
dely = ytmp - x[j][1];
delz = ztmp - x[j][2];
rsq = delx*delx + dely*dely + delz*delz;
jtype = type[j];
radj = atom->radius[j];
if (rsq < cutsq[itype][jtype]) {
r = sqrt(rsq);
// angular momentum = I*omega = 2/5 * M*R^2 * omega
wj[0] = omega[j][0];
wj[1] = omega[j][1];
wj[2] = omega[j][2];
// xl = point of closest approach on particle i from its center
xl[0] = -delx/r*radi;
xl[1] = -dely/r*radi;
xl[2] = -delz/r*radi;
jl[0] = -delx/r*radj;
jl[1] = -dely/r*radj;
jl[2] = -delz/r*radj;
// velocity at the point of closest approach on both particles
// v = v + omega_cross_xl - Ef.xl
// particle i
vi[0] = v[i][0] + (wi[1]*xl[2] - wi[2]*xl[1])
- (Ef[0][0]*xl[0] + Ef[0][1]*xl[1] + Ef[0][2]*xl[2]);
vi[1] = v[i][1] + (wi[2]*xl[0] - wi[0]*xl[2])
- (Ef[1][0]*xl[0] + Ef[1][1]*xl[1] + Ef[1][2]*xl[2]);
vi[2] = v[i][2] + (wi[0]*xl[1] - wi[1]*xl[0])
- (Ef[2][0]*xl[0] + Ef[2][1]*xl[1] + Ef[2][2]*xl[2]);
// particle j
vj[0] = v[j][0] - (wj[1]*jl[2] - wj[2]*jl[1])
+ (Ef[0][0]*jl[0] + Ef[0][1]*jl[1] + Ef[0][2]*jl[2]);
vj[1] = v[j][1] - (wj[2]*jl[0] - wj[0]*jl[2])
+ (Ef[1][0]*jl[0] + Ef[1][1]*jl[1] + Ef[1][2]*jl[2]);
vj[2] = v[j][2] - (wj[0]*jl[1] - wj[1]*jl[0])
+ (Ef[2][0]*jl[0] + Ef[2][1]*jl[1] + Ef[2][2]*jl[2]);
// scalar resistances XA and YA
h_sep = r - radi-radj;
// check for overlaps
if (h_sep < 0.0) overlaps++;
// if less than the minimum gap use the minimum gap instead
if (r < cut_inner[itype][jtype])
h_sep = cut_inner[itype][jtype] - radi-radj;
// scale h_sep by radi
h_sep = h_sep/radi;
beta0 = radj/radi;
beta1 = 1.0 + beta0;
// scalar resistances
if (flaglog) {
a_sq = beta0*beta0/beta1/beta1/h_sep +
(1.0+7.0*beta0+beta0*beta0)/5.0/pow(beta1,3)*log(1.0/h_sep);
a_sq += (1.0+18.0*beta0-29.0*beta0*beta0+18.0 *
pow(beta0,3)+pow(beta0,4))/21.0/pow(beta1,4) *
h_sep*log(1.0/h_sep);
a_sq *= 6.0*MY_PI*mu*radi;
a_sh = 4.0*beta0*(2.0+beta0+2.0*beta0*beta0)/15.0/pow(beta1,3) *
log(1.0/h_sep);
a_sh += 4.0*(16.0-45.0*beta0+58.0*beta0*beta0-45.0*pow(beta0,3) +
16.0*pow(beta0,4))/375.0/pow(beta1,4) *
h_sep*log(1.0/h_sep);
a_sh *= 6.0*MY_PI*mu*radi;
a_pu = beta0*(4.0+beta0)/10.0/beta1/beta1*log(1.0/h_sep);
a_pu += (32.0-33.0*beta0+83.0*beta0*beta0+43.0 *
pow(beta0,3))/250.0/pow(beta1,3)*h_sep*log(1.0/h_sep);
a_pu *= 8.0*MY_PI*mu*pow(radi,3);
} else a_sq = 6.0*MY_PI*mu*radi*(beta0*beta0/beta1/beta1/h_sep);
// relative velocity at the point of closest approach
// includes fluid velocity
vr1 = vi[0] - vj[0];
vr2 = vi[1] - vj[1];
vr3 = vi[2] - vj[2];
// normal component (vr.n)n
vnnr = (vr1*delx + vr2*dely + vr3*delz)/r;
vn1 = vnnr*delx/r;
vn2 = vnnr*dely/r;
vn3 = vnnr*delz/r;
// tangential component vr - (vr.n)n
vt1 = vr1 - vn1;
vt2 = vr2 - vn2;
vt3 = vr3 - vn3;
// force due to squeeze type motion
fx = a_sq*vn1;
fy = a_sq*vn2;
fz = a_sq*vn3;
// force due to all shear kind of motions
if (flaglog) {
fx = fx + a_sh*vt1;
fy = fy + a_sh*vt2;
fz = fz + a_sh*vt3;
}
// scale forces for appropriate units
fx *= vxmu2f;
fy *= vxmu2f;
fz *= vxmu2f;
// add to total force
f[i][0] -= fx;
f[i][1] -= fy;
f[i][2] -= fz;
// torque due to this force
if (flaglog) {
tx = xl[1]*fz - xl[2]*fy;
ty = xl[2]*fx - xl[0]*fz;
tz = xl[0]*fy - xl[1]*fx;
torque[i][0] -= vxmu2f*tx;
torque[i][1] -= vxmu2f*ty;
torque[i][2] -= vxmu2f*tz;
// torque due to a_pu
wdotn = ((wi[0]-wj[0])*delx + (wi[1]-wj[1])*dely +
(wi[2]-wj[2])*delz)/r;
wt1 = (wi[0]-wj[0]) - wdotn*delx/r;
wt2 = (wi[1]-wj[1]) - wdotn*dely/r;
wt3 = (wi[2]-wj[2]) - wdotn*delz/r;
tx = a_pu*wt1;
ty = a_pu*wt2;
tz = a_pu*wt3;
torque[i][0] -= vxmu2f*tx;
torque[i][1] -= vxmu2f*ty;
torque[i][2] -= vxmu2f*tz;
}
// set j = nlocal so that only I gets tallied
if (evflag) ev_tally_xyz(i,nlocal,nlocal,0,
0.0,0.0,-fx,-fy,-fz,delx,dely,delz);
}
}
}
// restore streaming component of velocity, omega, angmom
if (shearing) {
double *h_rate = domain->h_rate;
double *h_ratelo = domain->h_ratelo;
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
itype = type[i];
radi = atom->radius[i];
domain->x2lamda(x[i],lamda);
vstream[0] = h_rate[0]*lamda[0] + h_rate[5]*lamda[1] +
h_rate[4]*lamda[2] + h_ratelo[0];
vstream[1] = h_rate[1]*lamda[1] + h_rate[3]*lamda[2] + h_ratelo[1];
vstream[2] = h_rate[2]*lamda[2] + h_ratelo[2];
v[i][0] += vstream[0];
v[i][1] += vstream[1];
v[i][2] += vstream[2];
omega[i][0] -= 0.5*h_rate[3];
omega[i][1] += 0.5*h_rate[4];
omega[i][2] -= 0.5*h_rate[5];
}
}
// to DEBUG: set print_overlaps to 1
int print_overlaps = 0;
if (print_overlaps) {
int overlaps_all;
MPI_Allreduce(&overlaps,&overlaps_all,1,MPI_INT,MPI_SUM,world);
if (overlaps_all && comm->me == 0)
printf("Number of overlaps = %d\n",overlaps);
}
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void PairLubricatePoly::init_style()
{
if (force->newton_pair == 1)
error->all(FLERR,"Pair lubricate/poly requires newton pair off");
if (comm->ghost_velocity == 0)
error->all(FLERR,
"Pair lubricate/poly requires ghost atoms store velocity");
if (!atom->sphere_flag)
error->all(FLERR,"Pair lubricate/poly requires atom style sphere");
// insure all particles are finite-size
// for pair hybrid, should limit test to types using the pair style
double *radius = atom->radius;
int *type = atom->type;
int nlocal = atom->nlocal;
for (int i = 0; i < nlocal; i++)
if (radius[i] == 0.0)
error->one(FLERR,"Pair lubricate/poly requires extended particles");
int irequest = neighbor->request(this);
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->full = 1;
// set the isotropic constants that depend on the volume fraction
// vol_T = total volume
double vol_T = domain->xprd*domain->yprd*domain->zprd;
double volP = 0.0;
for (int i = 0; i < nlocal; i++)
volP += (4.0/3.0)*MY_PI*pow(atom->radius[i],3);
double vol_P;
MPI_Allreduce(&volP,&vol_P,1,MPI_DOUBLE,MPI_SUM,world);
double vol_f = vol_P/vol_T;
// set isotropic constants
if (flaglog == 0) {
R0 = 6*MY_PI*mu*(1.0 + 2.16*vol_f);
RT0 = 8*MY_PI*mu;
RS0 = 20.0/3.0*MY_PI*mu*(1.0 + 3.33*vol_f + 2.80*vol_f*vol_f);
} else {
R0 = 6*MY_PI*mu*(1.0 + 2.725*vol_f - 6.583*vol_f*vol_f);
RT0 = 8*MY_PI*mu*(1.0 + 0.749*vol_f - 2.469*vol_f*vol_f);
RS0 = 20.0/3.0*MY_PI*mu*(1.0 + 3.64*vol_f - 6.95*vol_f*vol_f);
}
// check for fix deform, if exists it must use "remap v"
shearing = 0;
for (int i = 0; i < modify->nfix; i++)
if (strcmp(modify->fix[i]->style,"deform") == 0) {
shearing = 1;
if (((FixDeform *) modify->fix[i])->remapflag != V_REMAP)
error->all(FLERR,"Using pair lubricate/poly with inconsistent "
"fix deform remap option");
}
// set Ef = 0 since used whether shearing or not
Ef[0][0] = Ef[0][1] = Ef[0][2] = 0.0;
Ef[1][0] = Ef[1][1] = Ef[1][2] = 0.0;
Ef[2][0] = Ef[2][1] = Ef[2][2] = 0.0;
}
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