int main() {
auto lbmodel = std::make_unique<LBModel>("D2Q9");
float rholocal = 1.0f;
std::array<float, 3> ulocal = {0.5, 0.5, -0.5};
std::vector<float> nlocal(lbmodel->get_num_directions(), 0.0f);
// Get eqlb dist
auto eqlbdist = std::make_unique<EqlbDist>(lbmodel.get());
(*eqlbdist)(rholocal, ulocal, nlocal);
// Expected value of eqlb dist
std::vector<float> nexpected = {
-0.05555555597, 0.277777791, -0.05555555597, -0.05555555597,
0.277777791, -0.003472222248, -0.003472222248, 0.2048611194,
0.03819444403
};
// Error
auto err = 0.0f;
for (auto k = 0; k < 9; ++k) {
auto tmp = nexpected[k] - nlocal[k];
err += tmp*tmp;
}
assert(err == 0.0f);
}
//--------------------------------------------------------
// apply_charged_surfaces
//--------------------------------------------------------
void ChargeRegulatorMethodEffectiveCharge::apply_local_forces()
{
double * q = lammpsInterface_->atom_charge();
_atomElectricalForce_.resize(nlocal(),nsd_);
double penalty = poissonSolver_->penalty_coefficient();
if (penalty <= 0.0) throw ATC_Error("ExtrinsicModelElectrostatic::apply_charged_surfaces expecting non zero penalty");
double dx[3];
const DENS_MAT & xa((interscaleManager_->per_atom_quantity("AtomicCoarseGrainingPositions"))->quantity());
// WORKSPACE - most are static
SparseVector<double> dv(nNodes_);
vector<SparseVector<double> > derivativeVectors;
derivativeVectors.reserve(nsd_);
const SPAR_MAT_VEC & shapeFunctionDerivatives((interscaleManager_->vector_sparse_matrix("InterpolateGradient"))->quantity());
DenseVector<INDEX> nodeIndices;
DENS_VEC nodeValues;
NODE_TO_XF_MAP::const_iterator inode;
for (inode = nodeXFMap_.begin(); inode != nodeXFMap_.end(); inode++) {
int node = inode->first;
DENS_VEC xI = (inode->second).first;
double qI = (inode->second).second;
double phiI = nodalChargePotential_[node];
for (int i = 0; i < nlocal(); i++) {
int atom = (atc_->internal_to_atom_map())(i);
double qa = q[atom];
if (qa != 0) {
double dxSq = 0.;
for (int j = 0; j < nsd_; j++) {
dx[j] = xa(i,j) - xI(j);
dxSq += dx[j]*dx[j];
}
if (dxSq < rCsq_) {
// first apply pairwise coulombic interaction
if (!useSlab_) {
double coulForce = qqrd2e_*qI*qa/(dxSq*sqrtf(dxSq));
for (int j = 0; j < nsd_; j++) {
_atomElectricalForce_(i,j) += dx[j]*coulForce; }
}
// second correct for FE potential induced by BCs
// determine shape function derivatives at atomic location
// and construct sparse vectors to store derivative data
for (int j = 0; j < nsd_; j++) {
shapeFunctionDerivatives[j]->row(i,nodeValues,nodeIndices);
derivativeVectors.push_back(dv);
for (int k = 0; k < nodeIndices.size(); k++) {
derivativeVectors[j](nodeIndices(k)) = nodeValues(k); }
}
// compute greens function from charge quadrature
SparseVector<double> shortFePotential(nNodes_);
shortFePotential.add_scaled(greensFunctions_[node],penalty*phiI);
// compute electric field induced by charge
DENS_VEC efield(nsd_);
for (int j = 0; j < nsd_; j++) {
efield(j) = -.1*dot(derivativeVectors[j],shortFePotential); }
// apply correction in atomic forces
double c = qV2e_*qa;
for (int j = 0; j < nsd_; j++) {
if ((!useSlab_) || (j==nsd_)) {
_atomElectricalForce_(i,j) -= c*efield(j);
}
}
}
}
}
}
}