258 lines
7.5 KiB
C++
258 lines
7.5 KiB
C++
// clang-format off
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/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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https://www.lammps.org/, Sandia National Laboratories
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LAMMPS development team: developers@lammps.org
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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 "pair_sph_idealgas.h"
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#include <cmath>
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#include "atom.h"
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#include "force.h"
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#include "neigh_list.h"
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#include "memory.h"
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#include "error.h"
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#include "domain.h"
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using namespace LAMMPS_NS;
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/* ---------------------------------------------------------------------- */
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PairSPHIdealGas::PairSPHIdealGas(LAMMPS *lmp) : Pair(lmp)
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{
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restartinfo = 0;
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}
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/* ---------------------------------------------------------------------- */
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PairSPHIdealGas::~PairSPHIdealGas() {
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if (allocated) {
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memory->destroy(setflag);
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memory->destroy(cutsq);
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memory->destroy(cut);
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memory->destroy(viscosity);
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}
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}
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/* ---------------------------------------------------------------------- */
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void PairSPHIdealGas::compute(int eflag, int vflag) {
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int i, j, ii, jj, inum, jnum, itype, jtype;
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double xtmp, ytmp, ztmp, delx, dely, delz, fpair;
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int *ilist, *jlist, *numneigh, **firstneigh;
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double vxtmp, vytmp, vztmp, imass, jmass, fi, fj, fvisc, h, ih, ihsq;
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double rsq, wfd, delVdotDelR, mu, deltaE, ci, cj;
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ev_init(eflag, vflag);
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double **v = atom->vest;
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double **x = atom->x;
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double **f = atom->f;
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double *rho = atom->rho;
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double *mass = atom->mass;
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double *desph = atom->desph;
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double *esph = atom->esph;
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double *drho = atom->drho;
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int *type = atom->type;
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int nlocal = atom->nlocal;
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int newton_pair = force->newton_pair;
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inum = list->inum;
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ilist = list->ilist;
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numneigh = list->numneigh;
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firstneigh = list->firstneigh;
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// loop over neighbors of my atoms
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for (ii = 0; ii < inum; ii++) {
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i = ilist[ii];
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xtmp = x[i][0];
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ytmp = x[i][1];
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ztmp = x[i][2];
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vxtmp = v[i][0];
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vytmp = v[i][1];
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vztmp = v[i][2];
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itype = type[i];
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jlist = firstneigh[i];
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jnum = numneigh[i];
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imass = mass[itype];
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fi = 0.4 * esph[i] / imass / rho[i]; // ideal gas EOS; this expression is fi = pressure / rho^2
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ci = sqrt(0.4*esph[i]/imass); // speed of sound with heat capacity ratio gamma=1.4
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for (jj = 0; jj < jnum; jj++) {
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j = jlist[jj];
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j &= NEIGHMASK;
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delx = xtmp - x[j][0];
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dely = ytmp - x[j][1];
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delz = ztmp - x[j][2];
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rsq = delx * delx + dely * dely + delz * delz;
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jtype = type[j];
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jmass = mass[jtype];
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if (rsq < cutsq[itype][jtype]) {
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h = cut[itype][jtype];
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ih = 1. / h;
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ihsq = ih * ih;
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wfd = h - sqrt(rsq);
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if (domain->dimension == 3) {
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// Lucy Kernel, 3d
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// Note that wfd, the derivative of the weight function with respect to r,
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// is lacking a factor of r.
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// The missing factor of r is recovered by
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// (1) using delV . delX instead of delV . (delX/r) and
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// (2) using f[i][0] += delx * fpair instead of f[i][0] += (delx/r) * fpair
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wfd = -25.066903536973515383e0 * wfd * wfd * ihsq * ihsq * ihsq * ih;
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} else {
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// Lucy Kernel, 2d
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wfd = -19.098593171027440292e0 * wfd * wfd * ihsq * ihsq * ihsq;
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}
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fj = 0.4 * esph[j] / jmass / rho[j];
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// dot product of velocity delta and distance vector
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delVdotDelR = delx * (vxtmp - v[j][0]) + dely * (vytmp - v[j][1])
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+ delz * (vztmp - v[j][2]);
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// artificial viscosity (Monaghan 1992)
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if (delVdotDelR < 0.) {
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cj = sqrt(0.4*esph[j]/jmass);
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mu = h * delVdotDelR / (rsq + 0.01 * h * h);
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fvisc = -viscosity[itype][jtype] * (ci + cj) * mu / (rho[i] + rho[j]);
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} else {
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fvisc = 0.;
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}
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// total pair force & thermal energy increment
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fpair = -imass * jmass * (fi + fj + fvisc) * wfd;
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deltaE = -0.5 * fpair * delVdotDelR;
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f[i][0] += delx * fpair;
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f[i][1] += dely * fpair;
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f[i][2] += delz * fpair;
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// and change in density
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drho[i] += jmass * delVdotDelR * wfd;
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// change in thermal energy
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desph[i] += deltaE;
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if (newton_pair || j < nlocal) {
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f[j][0] -= delx * fpair;
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f[j][1] -= dely * fpair;
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f[j][2] -= delz * fpair;
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desph[j] += deltaE;
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drho[j] += imass * delVdotDelR * wfd;
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}
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if (evflag)
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ev_tally(i, j, nlocal, newton_pair, 0.0, 0.0, fpair, delx, dely, delz);
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if (evflag)
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ev_tally(i, j, nlocal, newton_pair, 0.0, 0.0, fpair, delx, dely,
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delz);
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}
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}
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}
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if (vflag_fdotr) virial_fdotr_compute();
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}
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/* ----------------------------------------------------------------------
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allocate all arrays
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------------------------------------------------------------------------- */
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void PairSPHIdealGas::allocate() {
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allocated = 1;
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int n = atom->ntypes;
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memory->create(setflag, n + 1, n + 1, "pair:setflag");
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for (int i = 1; i <= n; i++)
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for (int j = i; j <= n; j++)
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setflag[i][j] = 0;
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memory->create(cutsq, n + 1, n + 1, "pair:cutsq");
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memory->create(cut, n + 1, n + 1, "pair:cut");
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memory->create(viscosity, n + 1, n + 1, "pair:viscosity");
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}
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/* ----------------------------------------------------------------------
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global settings
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------------------------------------------------------------------------- */
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void PairSPHIdealGas::settings(int narg, char **/*arg*/) {
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if (narg != 0)
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error->all(FLERR,
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"Illegal number of arguments for pair_style sph/idealgas");
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}
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/* ----------------------------------------------------------------------
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set coeffs for one or more type pairs
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------------------------------------------------------------------------- */
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void PairSPHIdealGas::coeff(int narg, char **arg) {
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if (narg != 4)
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error->all(FLERR,"Incorrect number of args for pair_style sph/idealgas coefficients");
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if (!allocated)
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allocate();
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int ilo, ihi, jlo, jhi;
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utils::bounds(FLERR,arg[0], 1, atom->ntypes, ilo, ihi, error);
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utils::bounds(FLERR,arg[1], 1, atom->ntypes, jlo, jhi, error);
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double viscosity_one = utils::numeric(FLERR,arg[2],false,lmp);
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double cut_one = utils::numeric(FLERR,arg[3],false,lmp);
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int count = 0;
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for (int i = ilo; i <= ihi; i++) {
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for (int j = MAX(jlo,i); j <= jhi; j++) {
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viscosity[i][j] = viscosity_one;
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//printf("setting cut[%d][%d] = %f\n", i, j, cut_one);
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cut[i][j] = cut_one;
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setflag[i][j] = 1;
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count++;
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}
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}
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if (count == 0)
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error->all(FLERR,"Incorrect args for pair sph/idealgas coefficients");
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}
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/* ----------------------------------------------------------------------
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init for one type pair i,j and corresponding j,i
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------------------------------------------------------------------------- */
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double PairSPHIdealGas::init_one(int i, int j) {
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if (setflag[i][j] == 0) {
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error->all(FLERR,"All pair sph/idealgas coeffs are not set");
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}
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cut[j][i] = cut[i][j];
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return cut[i][j];
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}
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/* ---------------------------------------------------------------------- */
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double PairSPHIdealGas::single(int /*i*/, int /*j*/, int /*itype*/, int /*jtype*/,
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double /*rsq*/, double /*factor_coul*/, double /*factor_lj*/, double &fforce) {
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fforce = 0.0;
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return 0.0;
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}
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