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Fix MLMG::getGradSolution & getFluxes for inhomogeneous Neumann and R…
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…obin BC

Because of the way how inhomogeneous and Robin BC are handled, we must add
the inhomogeneous fluxes back, otherwise they would be zero at those
boundaries.
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@WeiqunZhang
WeiqunZhang committed Oct 11, 2022
1 parent 5acfe07 commit 76e058b
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Showing 5 changed files with 164 additions and 0 deletions.
4 changes: 4 additions & 0 deletions Src/LinearSolvers/MLMG/AMReX_MLCellABecLap.H
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Expand Up @@ -61,6 +61,10 @@ public:

virtual void applyInhomogNeumannTerm (int amrlev, Any& rhs) const final override;

virtual void addInhomogNeumannFlux (
int amrlev, const Array<MultiFab*,AMREX_SPACEDIM>& grad,
MultiFab const& sol, bool mult_bcoef) const final override;

virtual void applyOverset (int amlev, Any& rhs) const override;

#if defined(AMREX_USE_HYPRE) && (AMREX_SPACEDIM > 1)
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111 changes: 111 additions & 0 deletions Src/LinearSolvers/MLMG/AMReX_MLCellABecLap.cpp
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Expand Up @@ -189,6 +189,7 @@ MLCellABecLap::getFluxes (const Vector<Array<MultiFab*,AMREX_SPACEDIM> >& a_flux
a_flux[alev][idim]->mult(betainv);
}
}
addInhomogNeumannFlux(alev, a_flux[alev], *a_sol[alev], true);
}
}

Expand Down Expand Up @@ -416,6 +417,116 @@ MLCellABecLap::applyInhomogNeumannTerm (int amrlev, Any& a_rhs) const
}
}

void
MLCellABecLap::addInhomogNeumannFlux (
int amrlev, const Array<MultiFab*,AMREX_SPACEDIM>& grad, MultiFab const& sol,
bool mult_bcoef) const
{
/*
* if (mult_bcoef == true)
* grad is -bceof*grad phi
* else
* grad is grad phi
*/
Real fac = mult_bcoef ? Real(-1.0) : Real(1.0);

bool has_inhomog_neumann = hasInhomogNeumannBC();
bool has_robin = hasRobinBC();

if (!has_inhomog_neumann && !has_robin) return;

int ncomp = getNComp();
const int mglev = 0;

const auto dxinv = m_geom[amrlev][mglev].InvCellSize();
const Box domain = m_geom[amrlev][mglev].growPeriodicDomain(1);

Array<MultiFab const*, AMREX_SPACEDIM> bcoef = {AMREX_D_DECL(nullptr,nullptr,nullptr)};
if (mult_bcoef) {
bcoef = getBCoeffs(amrlev,mglev);
}

const auto& bndry = *m_bndry_sol[amrlev];

MFItInfo mfi_info;
if (Gpu::notInLaunchRegion()) mfi_info.SetDynamic(true);

#ifdef AMREX_USE_OMP
#pragma omp parallel if (Gpu::notInLaunchRegion())
#endif
for (MFIter mfi(sol, mfi_info); mfi.isValid(); ++mfi)
{
Box const& vbx = mfi.validbox();
for (OrientationIter orit; orit.isValid(); ++orit) {
const Orientation ori = orit();
const int idim = ori.coordDir();
const Box& ccb = amrex::adjCell(vbx, ori);
const Dim3 os = IntVect::TheDimensionVector(idim).dim3();
const Real dxi = dxinv[idim];
if (! domain.contains(ccb)) {
for (int icomp = 0; icomp < ncomp; ++icomp) {
auto const& phi = sol.const_array(mfi,icomp);
auto const bv = bndry.bndryValues(ori).multiFab().const_array(mfi,icomp);
auto const bc = bcoef[idim] ? bcoef[idim]->const_array(mfi,icomp)
: Array4<Real const>{};
auto const& f = grad[idim]->array(mfi,icomp);
if (ori.isLow()) {
if (m_lobc_orig[icomp][idim] ==
LinOpBCType::inhomogNeumann) {
AMREX_HOST_DEVICE_FOR_3D(ccb, i, j, k,
{
int ii = i+os.x;
int jj = j+os.y;
int kk = k+os.z;
Real b = bc ? bc(ii,jj,kk) : Real(1.0);
f(ii,jj,kk) = fac*b*bv(i,j,k);
});
} else if (m_lobc_orig[icomp][idim] ==
LinOpBCType::Robin) {
Array4<Real const> const& rbc = (*m_robin_bcval[amrlev])[mfi].const_array(icomp*3);
AMREX_HOST_DEVICE_FOR_3D(ccb, i, j, k,
{
int ii = i+os.x;
int jj = j+os.y;
int kk = k+os.z;
Real tmp = Real(1.0) /
(rbc(i,j,k,1)*dxi + rbc(i,j,k,0)*Real(0.5));
Real RA = rbc(i,j,k,2) * tmp;
Real RB = (rbc(i,j,k,1)*dxi - rbc(i,j,k,0)*Real(0.5)) * tmp;
Real b = bc ? bc(ii,jj,kk) : Real(1.0);
f(ii,jj,kk) = fac*b*dxi*((Real(1.0)-RB)*phi(ii,jj,kk)-RA);
});
}
} else {
if (m_hibc_orig[icomp][idim] ==
LinOpBCType::inhomogNeumann) {
AMREX_HOST_DEVICE_FOR_3D(ccb, i, j, k,
{
Real b = bc ? bc(i,j,k) : Real(1.0);
f(i,j,k) = fac*b*bv(i,j,k);
});
} else if (m_hibc_orig[icomp][idim] ==
LinOpBCType::Robin) {
Array4<Real const> const& rbc = (*m_robin_bcval[amrlev])[mfi].const_array(icomp*3);
AMREX_HOST_DEVICE_FOR_3D(ccb, i, j, k,
{
Real tmp = Real(1.0) /
(rbc(i,j,k,1)*dxi + rbc(i,j,k,0)*Real(0.5));
Real RA = rbc(i,j,k,2) * tmp;
Real RB = (rbc(i,j,k,1)*dxi - rbc(i,j,k,0)*Real(0.5)) * tmp;
Real b = bc ? bc(i,j,k) : Real(1.0);
f(i,j,k) = fac*b*dxi*(RA+(RB-Real(1.0))*
phi(i-os.x,j-os.y,k-os.z));
});
}
}
}
}
}
}
}


void
MLCellABecLap::applyOverset (int amrlev, Any& a_rhs) const
{
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42 changes: 42 additions & 0 deletions Src/LinearSolvers/MLMG/AMReX_MLCellABecLap_K.H
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Expand Up @@ -12,4 +12,46 @@
#include <AMReX_MLCellABecLap_3D_K.H>
#endif

namespace amrex {

#if 0
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
void mlcellabec_add_innu_xlo (int i, int j, int k, int n, Array<Real> const& fx,
Array<Real const> const& bcoef,
Array4<Real const> const& bcval) noexcept
{
Real b = bcoef ? bcoef(i,j,k,n) : Real(1.0);
fx(i,j,k,n) = -b*bcval(i-1,j,k,icomp);
}

AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
void mlcellabec_add_innu_ylo (int i, int j, int k, int n, Array<Real> const& fy,
Array<Real const> const& bcoef,
Array4<Real const> const& bcval) noexcept
{
Real b = bcoef ? bcoef(i,j,k,n) : Real(1.0);
fy(i,j,k,n) = -b*bcval(i,j-1,k,icomp);
}

AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
void mlcellabec_add_innu_zlo (int i, int j, int k, int n, Array<Real> const& fz,
Array<Real const> const& bcoef,
Array4<Real const> const& bcval) noexcept
{
Real b = bcoef ? bcoef(i,j,k,n) : Real(1.0);
fz(i,j,k,n) = -b*bcval(i,j,k-1,icomp);
}

AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
void mlcellabec_add_innu_hi (int i, int j, int k, int n, Array<Real> const& f,
Array<Real const> const& bcoef,
Array4<Real const> const& bcval) noexcept
{
Real b = bcoef ? bcoef(i,j,k,n) : Real(1.0);
f(i,j,k,n) = -b*bcval(i,j,k,icomp);
}
#endif

}

#endif
5 changes: 5 additions & 0 deletions Src/LinearSolvers/MLMG/AMReX_MLCellLinOp.H
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Expand Up @@ -164,6 +164,11 @@ public:

virtual void AnyAverageDownAndSync (Vector<Any>& sol) const override;

virtual void addInhomogNeumannFlux (int /*amrlev*/,
const Array<MultiFab*,AMREX_SPACEDIM>& /*grad*/,
MultiFab const& /*sol*/,
bool /*mult_bcoef*/) const {}

struct BCTL {
BoundCond type;
Real location;
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2 changes: 2 additions & 0 deletions Src/LinearSolvers/MLMG/AMReX_MLCellLinOp.cpp
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Expand Up @@ -938,6 +938,8 @@ MLCellLinOp::compGrad (int amrlev, const Array<MultiFab*,AMREX_SPACEDIM>& grad,
});
#endif
}

addInhomogNeumannFlux(amrlev, grad, sol, false);
}

void
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