Diffusion.h

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///////////////////////////////////////////////////////////////////////////////
//
// File: Diffusion.h
//
// For more information, please see: http://www.nektar.info
//
// The MIT License
//
// Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
// Department of Aeronautics, Imperial College London (UK), and Scientific
// Computing and Imaging Institute, University of Utah (USA).
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// Description: Abstract base class for diffusion.
//
///////////////////////////////////////////////////////////////////////////////
 
#ifndef NEKTAR_SOLVERUTILS_DIFFUSION
#define NEKTAR_SOLVERUTILS_DIFFUSION
 
#include <functional>
#include <string>
 
#include <boost/core/ignore_unused.hpp>
 
#include <LibUtilities/BasicUtils/NekFactory.hpp>
#include <LibUtilities/BasicUtils/SharedArray.hpp>
#include <MultiRegions/AssemblyMap/AssemblyMapDG.h>
#include <MultiRegions/ExpList.h>
#include <SolverUtils/RiemannSolvers/RiemannSolver.h>
#include <SolverUtils/SolverUtilsDeclspec.h>
 
namespace Nektar
{
namespace SolverUtils
{
typedef std::function<void(const Array<OneD, Array<OneD, NekDouble>> &,
                           const TensorOfArray3D<NekDouble> &,
                           TensorOfArray3D<NekDouble> &)>
    DiffusionFluxVecCB;
 
typedef std::function<void(const Array<OneD, Array<OneD, NekDouble>> &,
                           TensorOfArray3D<NekDouble> &,
                           TensorOfArray3D<NekDouble> &)>
    DiffusionFluxVecCBNS;
 
typedef std::function<void(const Array<OneD, Array<OneD, NekDouble>> &,
                           const Array<OneD, Array<OneD, NekDouble>> &,
                           Array<OneD, Array<OneD, NekDouble>> &)>
    DiffusionFluxPenaltyNS;
 
/**
 * Parameter list meaning:
 *  1st: field conservative variables
 *  2th: Devrivatives of field conservative varialbes
 *  3rd: the current time for time-dependent boundary
 *  4th: Fwd of field conservative variables        optional
 *  5th: Fwd of Devrivatives(2nd)                   optional
 *
 * a null pointer need to be passed for optional parameters
 */
typedef std::function<void(
    const Array<OneD, const Array<OneD, NekDouble>> &,
    const Array<OneD, const Array<OneD, Array<OneD, NekDouble>>> &, NekDouble,
    const Array<OneD, const Array<OneD, NekDouble>> &,
    const Array<OneD, const Array<OneD, Array<OneD, NekDouble>>> &)>
    FunctorDerivBndCond;
 
/**
 * Parameter list meaning:
 *  1st: nvariables
 *  2nd: nspaceDimension
 *  3rd: field conservative variables
 *  4th: Devrivatives of field conservative varialbes
 *  5th: nonzero flux index array,          optional
 *  6th: normal vectors                     optional
 *
 * a null pointer need to be passed for optional parameters
 */
typedef std::function<void(
    const int, const Array<OneD, Array<OneD, NekDouble>> &,
    const TensorOfArray3D<NekDouble> &, TensorOfArray3D<NekDouble> &,
    Array<OneD, int> &, const Array<OneD, Array<OneD, NekDouble>> &)>
    DiffusionFluxCons;
 
/**
 * Parameter list meaning:
 *  1st: nvariables
 *  2nd: nspaceDimension
 *  3rd: trace conservative variables for Diffusion Flux Jacobian
 *  4th: trace conservative variables( usually the jump of trace value)
 *  5th: trace symmetric flux
 *  6th: nonzero flux index array,          optional
 *
 * a null pointer need to be passed for optional parameters
 */
typedef std::function<void(
    const int, const Array<OneD, Array<OneD, NekDouble>> &,
    const Array<OneD, Array<OneD, NekDouble>> &, TensorOfArray3D<NekDouble> &,
    Array<OneD, int> &, const Array<OneD, Array<OneD, NekDouble>> &)>
    DiffusionSymmFluxCons;
 
/**
 * Parameter list meaning:
 *  1rd: trace conservative variables
 */
typedef std::function<void(Array<OneD, Array<OneD, NekDouble>> &)>
    SpecialBndTreat;
 
class Diffusion
{
public:
    /// Params for Ducros sensor
    Array<OneD, NekDouble> m_divVel;
    Array<OneD, NekDouble> m_divVelSquare;
    Array<OneD, NekDouble> m_curlVelSquare;
 
    SOLVER_UTILS_EXPORT virtual ~Diffusion(){};
 
    SOLVER_UTILS_EXPORT void InitObject(
        LibUtilities::SessionReaderSharedPtr pSession,
        Array<OneD, MultiRegions::ExpListSharedPtr> pFields);
 
    SOLVER_UTILS_EXPORT void Diffuse(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd =
            NullNekDoubleArrayOfArray,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd =
            NullNekDoubleArrayOfArray);
 
    SOLVER_UTILS_EXPORT void DiffuseCoeffs(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd =
            NullNekDoubleArrayOfArray,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd =
            NullNekDoubleArrayOfArray);
 
    SOLVER_UTILS_EXPORT void Diffuse(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray, NekDouble time,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd =
            NullNekDoubleArrayOfArray,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd =
            NullNekDoubleArrayOfArray);
 
    SOLVER_UTILS_EXPORT void DiffuseCoeffs(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd,
        TensorOfArray3D<NekDouble> &qfield, Array<OneD, int> &nonZeroIndex)
    {
        v_DiffuseCoeffs(nConvectiveFields, fields, inarray, outarray, pFwd,
                        pBwd, qfield, nonZeroIndex);
    }
 
    SOLVER_UTILS_EXPORT void DiffuseCoeffs(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray, NekDouble time,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd =
            NullNekDoubleArrayOfArray,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd =
            NullNekDoubleArrayOfArray);
 
    // Diffusion Calculate the physical derivatives
    SOLVER_UTILS_EXPORT void DiffuseCalcDerivative(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfields,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd =
            NullNekDoubleArrayOfArray,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd =
            NullNekDoubleArrayOfArray);
 
    /// Diffusion Volume FLux
 
    SOLVER_UTILS_EXPORT void DiffuseVolumeFlux(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfields,
        TensorOfArray3D<NekDouble> &VolumeFlux,
        Array<OneD, int> &nonZeroIndex = NullInt1DArray)
    {
        v_DiffuseVolumeFlux(fields, inarray, qfields, VolumeFlux, nonZeroIndex);
    }
 
    /// Diffusion term Trace Flux
    SOLVER_UTILS_EXPORT void DiffuseTraceFlux(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfields,
        TensorOfArray3D<NekDouble> &VolumeFlux,
        Array<OneD, Array<OneD, NekDouble>> &TraceFlux,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd =
            NullNekDoubleArrayOfArray,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd =
            NullNekDoubleArrayOfArray,
        Array<OneD, int> &nonZeroIndex = NullInt1DArray)
    {
        v_DiffuseTraceFlux(fields, inarray, qfields, VolumeFlux, TraceFlux,
                           pFwd, pBwd, nonZeroIndex);
    }
 
    SOLVER_UTILS_EXPORT void DiffuseTraceSymmFlux(
        const int nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        const TensorOfArray3D<NekDouble> &qfield,
        const TensorOfArray3D<NekDouble> &VolumeFlux,
        TensorOfArray3D<NekDouble> &SymmFlux,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd,
        Array<OneD, int> &nonZeroIndex,
        Array<OneD, Array<OneD, NekDouble>> &solution_Aver =
            NullNekDoubleArrayOfArray,
        Array<OneD, Array<OneD, NekDouble>> &solution_jump =
            NullNekDoubleArrayOfArray)
    {
        v_DiffuseTraceSymmFlux(nConvectiveFields, fields, inarray, qfield,
                               VolumeFlux, SymmFlux, pFwd, pBwd, nonZeroIndex,
                               solution_Aver, solution_jump);
    }
 
    /// Add symmetric flux to field in coeff space
    SOLVER_UTILS_EXPORT void AddDiffusionSymmFluxToCoeff(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfield,
        TensorOfArray3D<NekDouble> &VolumeFlux,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd)
    {
        v_AddDiffusionSymmFluxToCoeff(nConvectiveFields, fields, inarray,
                                      qfield, VolumeFlux, outarray, pFwd, pBwd);
    }
 
    /// Add symmetric flux to field in coeff physical space
    SOLVER_UTILS_EXPORT void AddDiffusionSymmFluxToPhys(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfield,
        TensorOfArray3D<NekDouble> &VolumeFlux,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd)
    {
        v_AddDiffusionSymmFluxToPhys(nConvectiveFields, fields, inarray, qfield,
                                     VolumeFlux, outarray, pFwd, pBwd);
    }
 
    SOLVER_UTILS_EXPORT void AddSymmFluxIntegralToOffDiag(
        const int nConvectiveFields, const int nDim, const int nPts,
        const int nTracePts,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, const int> &nonZeroIndex,
        TensorOfArray3D<NekDouble> &Fwdflux,
        TensorOfArray3D<NekDouble> &Bwdflux,
        Array<OneD, Array<OneD, NekDouble>> &outarray);
 
    template <typename FuncPointerT, typename ObjectPointerT>
    void SetFluxVector(FuncPointerT func, ObjectPointerT obj)
    {
        m_fluxVector = std::bind(func, obj, std::placeholders::_1,
                                 std::placeholders::_2, std::placeholders::_3);
    }
 
    SOLVER_UTILS_EXPORT void SetFluxVector(DiffusionFluxVecCB fluxVector)
    {
        m_fluxVector = fluxVector;
    }
 
    template <typename FuncPointerT, typename ObjectPointerT>
    void SetFluxVectorNS(FuncPointerT func, ObjectPointerT obj)
    {
        m_fluxVectorNS =
            std::bind(func, obj, std::placeholders::_1, std::placeholders::_2,
                      std::placeholders::_3);
    }
 
    void SetFluxVectorNS(DiffusionFluxVecCBNS fluxVector)
    {
        m_fluxVectorNS = fluxVector;
    }
 
    template <typename FuncPointerT, typename ObjectPointerT>
    void SetFluxPenaltyNS(FuncPointerT func, ObjectPointerT obj)
    {
        m_fluxPenaltyNS =
            std::bind(func, obj, std::placeholders::_1, std::placeholders::_2,
                      std::placeholders::_3);
    }
 
    void SetFluxPenaltyNS(DiffusionFluxPenaltyNS flux)
    {
        m_fluxPenaltyNS = flux;
    }
 
    template <typename FuncPointerT, typename ObjectPointerT>
    void SetDiffusionFluxCons(FuncPointerT func, ObjectPointerT obj)
    {
        m_FunctorDiffusionfluxCons =
            std::bind(func, obj, std::placeholders::_1, std::placeholders::_2,
                      std::placeholders::_3, std::placeholders::_4,
                      std::placeholders::_5, std::placeholders::_6);
    }
 
    void SetDiffusionFluxCons(DiffusionFluxCons flux)
    {
        m_FunctorDiffusionfluxCons = flux;
    }
 
    template <typename FuncPointerT, typename ObjectPointerT>
    void SetDiffusionFluxConsTrace(FuncPointerT func, ObjectPointerT obj)
    {
        m_FunctorDiffusionfluxConsTrace =
            std::bind(func, obj, std::placeholders::_1, std::placeholders::_2,
                      std::placeholders::_3, std::placeholders::_4,
                      std::placeholders::_5, std::placeholders::_6);
    }
 
    void SetDiffusionFluxConsTrace(DiffusionFluxCons flux)
    {
        m_FunctorDiffusionfluxConsTrace = flux;
    }
 
    template <typename FuncPointerT, typename ObjectPointerT>
    void SetSpecialBndTreat(FuncPointerT func, ObjectPointerT obj)
    {
        m_SpecialBndTreat = std::bind(func, obj, std::placeholders::_1);
    }
 
    template <typename FuncPointerT, typename ObjectPointerT>
    void SetDiffusionSymmFluxCons(FuncPointerT func, ObjectPointerT obj)
    {
        m_FunctorSymmetricfluxCons =
            std::bind(func, obj, std::placeholders::_1, std::placeholders::_2,
                      std::placeholders::_3, std::placeholders::_4,
                      std::placeholders::_5, std::placeholders::_6);
    }
 
    inline void SetHomoDerivs(Array<OneD, Array<OneD, NekDouble>> &deriv)
    {
        v_SetHomoDerivs(deriv);
    }
 
    virtual TensorOfArray3D<NekDouble> &GetFluxTensor()
    {
        return v_GetFluxTensor();
    }
 
    /// Get the average and jump value of conservative variables on trace
    SOLVER_UTILS_EXPORT void ConsVarAveJump(
        const std::size_t nConvectiveFields, const size_t npnts,
        const Array<OneD, const Array<OneD, NekDouble>> &vFwd,
        const Array<OneD, const Array<OneD, NekDouble>> &vBwd,
        Array<OneD, Array<OneD, NekDouble>> &aver,
        Array<OneD, Array<OneD, NekDouble>> &jump)
    {
        v_ConsVarAveJump(nConvectiveFields, npnts, vFwd, vBwd, aver, jump);
    }
 
    /// Get trace normal
    SOLVER_UTILS_EXPORT const Array<OneD, const Array<OneD, NekDouble>>
        &GetTraceNormal()
    {
        return v_GetTraceNormal();
    }
 
protected:
    DiffusionFluxVecCB m_fluxVector;
    DiffusionFluxVecCBNS m_fluxVectorNS;
    DiffusionFluxPenaltyNS m_fluxPenaltyNS;
    DiffusionFluxCons m_FunctorDiffusionfluxCons;
    DiffusionFluxCons m_FunctorDiffusionfluxConsTrace;
    SpecialBndTreat m_SpecialBndTreat;
    DiffusionSymmFluxCons m_FunctorSymmetricfluxCons;
 
    NekDouble m_time = 0.0;
 
    SOLVER_UTILS_EXPORT virtual void v_InitObject(
        LibUtilities::SessionReaderSharedPtr pSession,
        Array<OneD, MultiRegions::ExpListSharedPtr> pFields)
    {
        boost::ignore_unused(pSession, pFields);
    };
 
    SOLVER_UTILS_EXPORT virtual void v_Diffuse(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd);
 
    SOLVER_UTILS_EXPORT virtual void v_DiffuseCoeffs(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd);
 
    SOLVER_UTILS_EXPORT virtual void v_DiffuseCoeffs(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &vFwd,
        const Array<OneD, Array<OneD, NekDouble>> &vBwd,
        TensorOfArray3D<NekDouble> &qfield, Array<OneD, int> &nonZeroIndex);
 
    SOLVER_UTILS_EXPORT virtual void v_ConsVarAveJump(
        const std::size_t nConvectiveFields, const size_t npnts,
        const Array<OneD, const Array<OneD, NekDouble>> &vFwd,
        const Array<OneD, const Array<OneD, NekDouble>> &vBwd,
        Array<OneD, Array<OneD, NekDouble>> &aver,
        Array<OneD, Array<OneD, NekDouble>> &jump);
 
    /// Diffusion Flux, calculate the physical derivatives
    SOLVER_UTILS_EXPORT virtual void v_DiffuseCalcDerivative(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfields,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd);
 
    /// Diffusion Volume Flux
    SOLVER_UTILS_EXPORT virtual void v_DiffuseVolumeFlux(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfields,
        TensorOfArray3D<NekDouble> &VolumeFlux, Array<OneD, int> &nonZeroIndex);
 
    /// Diffusion term Trace Flux
    SOLVER_UTILS_EXPORT virtual void v_DiffuseTraceFlux(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &Qfields,
        TensorOfArray3D<NekDouble> &VolumeFlux,
        Array<OneD, Array<OneD, NekDouble>> &TraceFlux,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd,
        Array<OneD, int> &nonZeroIndex);
 
    SOLVER_UTILS_EXPORT virtual void v_DiffuseTraceSymmFlux(
        const int nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        const TensorOfArray3D<NekDouble> &qfield,
        const TensorOfArray3D<NekDouble> &VolumeFlux,
        TensorOfArray3D<NekDouble> &SymmFlux,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd,
        Array<OneD, int> &nonZeroIndex,
        Array<OneD, Array<OneD, NekDouble>> &solution_Aver,
        Array<OneD, Array<OneD, NekDouble>> &solution_jump)
    {
        boost::ignore_unused(nConvectiveFields, fields, inarray, qfield,
                             VolumeFlux, SymmFlux, pFwd, pBwd, nonZeroIndex,
                             solution_Aver, solution_jump);
        ASSERTL0(false, "Not defined function v_DiffuseTraceSymmFlux.");
    }
 
    SOLVER_UTILS_EXPORT virtual void v_AddDiffusionSymmFluxToCoeff(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfield,
        TensorOfArray3D<NekDouble> &VolumeFlux,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd)
    {
        boost::ignore_unused(nConvectiveFields, fields, inarray, qfield,
                             VolumeFlux, outarray, pFwd, pBwd);
    }
    SOLVER_UTILS_EXPORT virtual void v_AddDiffusionSymmFluxToPhys(
        const std::size_t nConvectiveFields,
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        TensorOfArray3D<NekDouble> &qfield,
        TensorOfArray3D<NekDouble> &VolumeFlux,
        Array<OneD, Array<OneD, NekDouble>> &outarray,
        const Array<OneD, Array<OneD, NekDouble>> &pFwd,
        const Array<OneD, Array<OneD, NekDouble>> &pBwd)
    {
        boost::ignore_unused(nConvectiveFields, fields, inarray, qfield,
                             VolumeFlux, outarray, pFwd, pBwd);
    }
 
    virtual void v_SetHomoDerivs(Array<OneD, Array<OneD, NekDouble>> &deriv)
    {
        boost::ignore_unused(deriv);
    }
 
    virtual TensorOfArray3D<NekDouble> &v_GetFluxTensor()
    {
        static TensorOfArray3D<NekDouble> tmp;
        return tmp;
    }
 
    SOLVER_UTILS_EXPORT virtual const Array<OneD, const Array<OneD, NekDouble>>
        &v_GetTraceNormal();
 
    /// Compute primary derivatives
    SOLVER_UTILS_EXPORT virtual void v_GetPrimVar(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const Array<OneD, Array<OneD, NekDouble>> &inarray,
        Array<OneD, Array<OneD, NekDouble>> &primVar);
 
    /// Compute divergence and curl squared
    SOLVER_UTILS_EXPORT void GetDivCurl(
        const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
        const TensorOfArray3D<NekDouble> &pVarDer);
};
 
/// A shared pointer to an EquationSystem object
typedef std::shared_ptr<SolverUtils::Diffusion> DiffusionSharedPtr;
 
/// Datatype of the NekFactory used to instantiate classes derived
/// from the Diffusion class.
typedef LibUtilities::NekFactory<std::string, Diffusion, std::string>
    DiffusionFactory;
SOLVER_UTILS_EXPORT DiffusionFactory &GetDiffusionFactory();
} // namespace SolverUtils
} // namespace Nektar
 
#endif