upwind.hpp

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// SPDX-FileCopyrightText: 2023 - 2025 NeoN authors
//
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include "NeoN/fields/field.hpp"
#include "NeoN/core/executor/executor.hpp"
#include "NeoN/finiteVolume/cellCentred/interpolation/surfaceInterpolation.hpp"
#include "NeoN/mesh/unstructured/unstructuredMesh.hpp"
#include "NeoN/finiteVolume/cellCentred/stencil/geometryScheme.hpp"
 
#include <Kokkos_Core.hpp>
 
#include <functional>
 
namespace NeoN::finiteVolume::cellCentred
{
 
/* @brief computional kernel to perform an upwind interpolation
** from a source volumeVector to a surface field. It performs an interpolation
** of the form
**
** d_f = w_f * s_O + ( 1 - w_f ) * s_N where w_1 is either 0,1 depending on the
** direction of the flux
**
**@param src the input field
**@param weights weights for the interpolation
**@param dst the target field
*/
template<typename ValueType>
void computeUpwindInterpolation(
    const VolumeField<ValueType>& src,
    const SurfaceField<scalar>& flux,
    const SurfaceField<scalar>& weights,
    SurfaceField<ValueType>& dst
);
 
 
template<typename ValueType>
void computeUpwindInterpolationWeights(
    const SurfaceField<scalar>& flux,
    const VolumeField<ValueType>& src,
    SurfaceField<scalar>& weights
);
 
 
template<typename ValueType>
class Upwind : public SurfaceInterpolationFactory<ValueType>::template Register<Upwind<ValueType>>
{
 
    using Base = SurfaceInterpolationFactory<ValueType>::template Register<Upwind<ValueType>>;
 
public:
 
    Upwind(const Executor& exec, const UnstructuredMesh& mesh, [[maybe_unused]] Input input)
        : Base(exec, mesh), geometryScheme_(GeometryScheme::readOrCreate(mesh)) {};
 
    static std::string name() { return "upwind"; }
 
    static std::string doc() { return "upwind interpolation"; }
 
    static std::string schema() { return "none"; }
 
    void interpolate(
        [[maybe_unused]] const VolumeField<ValueType>& src,
        [[maybe_unused]] SurfaceField<ValueType>& dst
    ) const override
    {
        NF_ERROR_EXIT("limited scheme require a faceFlux");
    }
 
    void interpolate(
        const SurfaceField<scalar>& flux,
        const VolumeField<ValueType>& src,
        SurfaceField<ValueType>& dst
    ) const override
    {
        computeUpwindInterpolation(src, flux, geometryScheme_->weights(), dst);
    }
 
    // src weight
    void weight(const VolumeField<ValueType>&, SurfaceField<scalar>&) const override
    {
        NF_ERROR_EXIT("upwind interpolation scheme requires a faceFlux");
    }
 
    // flux, src, weight
    void weight(
        const SurfaceField<scalar>& faceFlux,
        const VolumeField<ValueType>& src,
        SurfaceField<scalar>& weights
    ) const override
    {
        computeUpwindInterpolationWeights(faceFlux, src, weights);
    }
 
    std::unique_ptr<SurfaceInterpolationFactory<ValueType>> clone() const override
    {
        return std::make_unique<Upwind>(*this);
    }
 
private:
 
    const std::shared_ptr<GeometryScheme> geometryScheme_;
};
 
} // namespace NeoN
 
 
namespace NeoN
{
 
namespace fvcc = finiteVolume::cellCentred;
 
template class fvcc::Upwind<scalar>;
template class fvcc::Upwind<Vec3>;
 
}