ArtificialDiffusion.cpp

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///////////////////////////////////////////////////////////////////////////////
//
// File: ArtificialDiffusion.cpp
//
// 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 compressible solver artificial diffusion
//              used for shock capturing artificial diffusion.
//
///////////////////////////////////////////////////////////////////////////////
 
#include "ArtificialDiffusion.h"
 
namespace Nektar
{
 
ArtificialDiffusionFactory &GetArtificialDiffusionFactory()
{
    static ArtificialDiffusionFactory instance;
    return instance;
}
 
ArtificialDiffusion::ArtificialDiffusion(
    const LibUtilities::SessionReaderSharedPtr &pSession,
    const Array<OneD, MultiRegions::ExpListSharedPtr> &pFields,
    const int spacedim)
    : m_session(pSession), m_fields(pFields)
{
    // Create auxiliary object to convert variables
    m_varConv = MemoryManager<VariableConverter>::AllocateSharedPtr(m_session,
                                                                    spacedim);
 
    m_diffusion =
        SolverUtils::GetDiffusionFactory().CreateInstance("LDG", "LDG");
    m_diffusion->SetFluxVector(&ArtificialDiffusion::GetFluxVector, this);
    m_diffusion->InitObject(m_session, m_fields);
 
    // Get constant scaling
    m_session->LoadParameter("mu0", m_mu0, 1.0);
}
 
/**
 *
 */
void ArtificialDiffusion::v_DoArtificialDiffusion(
    const Array<OneD, const Array<OneD, NekDouble>> &inarray,
    Array<OneD, Array<OneD, NekDouble>> &outarray)
{
    int nvariables = inarray.size();
    int npoints    = m_fields[0]->GetNpoints();
 
    Array<OneD, Array<OneD, NekDouble>> outarrayDiff(nvariables);
 
    for (int i = 0; i < nvariables; ++i)
    {
        outarrayDiff[i] = Array<OneD, NekDouble>(npoints, 0.0);
    }
 
    m_diffusion->Diffuse(nvariables, m_fields, inarray, outarrayDiff);
 
    for (int i = 0; i < nvariables; ++i)
    {
        Vmath::Vadd(npoints, outarray[i], 1, outarrayDiff[i], 1, outarray[i],
                    1);
    }
}
 
/**
 *
 */
void ArtificialDiffusion::v_DoArtificialDiffusionCoeff(
    const Array<OneD, const Array<OneD, NekDouble>> &inarray,
    Array<OneD, Array<OneD, NekDouble>> &outarray)
{
    size_t nvariables = inarray.size();
    size_t ncoeffs    = m_fields[0]->GetNcoeffs();
 
    Array<OneD, Array<OneD, NekDouble>> outarrayDiff{nvariables};
 
    for (size_t i = 0; i < nvariables; ++i)
    {
        outarrayDiff[i] = Array<OneD, NekDouble>{ncoeffs, 0.0};
    }
 
    m_diffusion->DiffuseCoeffs(nvariables, m_fields, inarray, outarrayDiff);
 
    for (size_t i = 0; i < nvariables; ++i)
    {
        Vmath::Vadd(ncoeffs, outarray[i], 1, outarrayDiff[i], 1, outarray[i],
                    1);
    }
}
 
/**
 * @brief Return the flux vector for the artificial viscosity operator.
 */
void ArtificialDiffusion::GetFluxVector(
    const Array<OneD, Array<OneD, NekDouble>> &inarray,
    const Array<OneD, Array<OneD, Array<OneD, NekDouble>>> &qfield,
    Array<OneD, Array<OneD, Array<OneD, NekDouble>>> &viscousTensor)
{
    unsigned int nDim              = qfield.size();
    unsigned int nConvectiveFields = qfield[0].size();
    unsigned int nPts              = qfield[0][0].size();
 
    // Get Artificial viscosity
    Array<OneD, NekDouble> mu{nPts, 0.0};
    GetArtificialViscosity(inarray, mu);
 
    // Compute viscous tensor
    for (unsigned int j = 0; j < nDim; ++j)
    {
        for (unsigned int i = 0; i < nConvectiveFields; ++i)
        {
            Vmath::Vmul(nPts, qfield[j][i], 1, mu, 1, viscousTensor[j][i], 1);
        }
    }
}
 
} // namespace Nektar