gaussGreenLaplacian.hpp

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// SPDX-FileCopyrightText: 2024 - 2025 NeoN authors
//
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include "NeoN/fields/field.hpp"
#include "NeoN/core/executor/executor.hpp"
#include "NeoN/mesh/unstructured/unstructuredMesh.hpp"
#include "NeoN/linearAlgebra/sparsityPattern.hpp"
#include "NeoN/finiteVolume/cellCentred/operators/laplacianOperator.hpp"
#include "NeoN/finiteVolume/cellCentred/interpolation/surfaceInterpolation.hpp"
#include "NeoN/finiteVolume/cellCentred/faceNormalGradient/faceNormalGradient.hpp"
 
namespace NeoN::finiteVolume::cellCentred
{
 
template<typename ValueType>
void computeLaplacianExp(
    const FaceNormalGradient<ValueType>&,
    const SurfaceField<scalar>&,
    VolumeField<ValueType>&,
    Vector<ValueType>&,
    const dsl::Coeff
);
 
template<typename ValueType>
void computeLaplacianImpl(
    la::LinearSystem<ValueType, localIdx>& ls,
    const SurfaceField<scalar>& gamma,
    VolumeField<ValueType>& phi,
    const dsl::Coeff operatorScaling,
    const la::SparsityPattern& sparsityPattern,
    const FaceNormalGradient<ValueType>& faceNormalGradient
);
 
template<typename ValueType>
class GaussGreenLaplacian :
    public LaplacianOperatorFactory<ValueType>::template Register<GaussGreenLaplacian<ValueType>>
{
    using Base =
        LaplacianOperatorFactory<ValueType>::template Register<GaussGreenLaplacian<ValueType>>;
 
public:
 
    static std::string name() { return "Gauss"; }
 
    static std::string doc() { return "Gauss-Green Laplacian"; }
 
    static std::string schema() { return "none"; }
 
    GaussGreenLaplacian(const Executor& exec, const UnstructuredMesh& mesh, const Input& inputs)
        : Base(exec, mesh), surfaceInterpolation_(exec, mesh, inputs),
          faceNormalGradient_(exec, mesh, inputs) {};
 
    virtual void laplacian(
        VolumeField<ValueType>& lapPhi,
        const SurfaceField<scalar>& gamma,
        VolumeField<ValueType>& phi,
        const dsl::Coeff operatorScaling
    ) override
    {
        computeLaplacianExp<ValueType>(
            faceNormalGradient_, gamma, phi, lapPhi.internalVector(), operatorScaling
        );
    };
 
    virtual VolumeField<ValueType> laplacian(
        const SurfaceField<scalar>& gamma,
        VolumeField<ValueType>& phi,
        const dsl::Coeff operatorScaling
    ) const override
    {
        std::string name = "laplacian(" + gamma.name + "," + phi.name + ")";
        VolumeField<ValueType> lapPhi(
            this->exec_,
            name,
            this->mesh_,
            createCalculatedBCs<VolumeBoundary<ValueType>>(this->mesh_)
        );
        NeoN::fill(lapPhi.internalVector(), zero<ValueType>());
        NeoN::fill(lapPhi.boundaryData().value(), zero<ValueType>());
        computeLaplacianExp<ValueType>(
            faceNormalGradient_, gamma, phi, lapPhi.internalVector(), operatorScaling
        );
        return lapPhi;
    };
 
    virtual void laplacian(
        Vector<ValueType>& lapPhi,
        const SurfaceField<scalar>& gamma,
        VolumeField<ValueType>& phi,
        const dsl::Coeff operatorScaling
    ) override
    {
        computeLaplacianExp<ValueType>(faceNormalGradient_, gamma, phi, lapPhi, operatorScaling);
    };
 
    virtual void laplacian(
        la::LinearSystem<ValueType, localIdx>& ls,
        const SurfaceField<scalar>& gamma,
        VolumeField<ValueType>& phi,
        const dsl::Coeff operatorScaling
    ) override
    {
        computeLaplacianImpl(
            ls, gamma, phi, operatorScaling, this->getSparsityPattern(), faceNormalGradient_
        );
    };
 
    std::unique_ptr<LaplacianOperatorFactory<ValueType>> clone() const override
    {
        return std::make_unique<GaussGreenLaplacian<ValueType>>(*this);
    };
 
private:
 
    SurfaceInterpolation<ValueType> surfaceInterpolation_;
 
    FaceNormalGradient<ValueType> faceNormalGradient_;
};
 
// instantiate the template class
template class GaussGreenLaplacian<scalar>;
template class GaussGreenLaplacian<Vec3>;
 
} // namespace NeoN