PressureOutflowBC.cpp

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///////////////////////////////////////////////////////////////////////////////
//
// File: PressureOutflowBC.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: Pressure outflow boundary condition
//
///////////////////////////////////////////////////////////////////////////////
 
#include "PressureOutflowBC.h"
 
using namespace std;
 
namespace Nektar
{
 
std::string PressureOutflowBC::className =
    GetCFSBndCondFactory().RegisterCreatorFunction(
        "PressureOutflow", PressureOutflowBC::create,
        "Pressure outflow boundary condition.");
 
PressureOutflowBC::PressureOutflowBC(
    const LibUtilities::SessionReaderSharedPtr &pSession,
    const Array<OneD, MultiRegions::ExpListSharedPtr> &pFields,
    const Array<OneD, Array<OneD, NekDouble>> &pTraceNormals,
    const int pSpaceDim, const int bcRegion, const int cnt)
    : CFSBndCond(pSession, pFields, pTraceNormals, pSpaceDim, bcRegion, cnt)
{
    int numBCPts =
        m_fields[0]->GetBndCondExpansions()[m_bcRegion]->GetNpoints();
    m_pressureStorage = Array<OneD, NekDouble>(numBCPts, 0.0);
 
    // Get Pressure
    Vmath::Vcopy(
        numBCPts,
        m_fields[m_spacedim + 1]->GetBndCondExpansions()[m_bcRegion]->GetPhys(),
        1, m_pressureStorage, 1);
}
 
void PressureOutflowBC::v_Apply(Array<OneD, Array<OneD, NekDouble>> &Fwd,
                                Array<OneD, Array<OneD, NekDouble>> &physarray,
                                [[maybe_unused]] const NekDouble &time)
{
    int i, j;
    int nTracePts   = m_fields[0]->GetTrace()->GetNpoints();
    int nVariables  = physarray.size();
    int nDimensions = m_spacedim;
 
    const Array<OneD, const int> &traceBndMap = m_fields[0]->GetTraceBndMap();
 
    // Computing the normal velocity for characteristics coming
    // from inside the computational domain
    Array<OneD, NekDouble> Vn(nTracePts, 0.0);
    Array<OneD, NekDouble> Vel(nTracePts, 0.0);
    for (i = 0; i < nDimensions; ++i)
    {
        Vmath::Vdiv(nTracePts, Fwd[i + 1], 1, Fwd[0], 1, Vel, 1);
        Vmath::Vvtvp(nTracePts, m_traceNormals[i], 1, Vel, 1, Vn, 1, Vn, 1);
    }
 
    // Computing the absolute value of the velocity in order to compute the
    // Mach number to decide whether supersonic or subsonic
    Array<OneD, NekDouble> absVel(nTracePts, 0.0);
    m_varConv->GetAbsoluteVelocity(Fwd, absVel);
 
    // Get speed of sound
    Array<OneD, NekDouble> soundSpeed(nTracePts);
    m_varConv->GetSoundSpeed(Fwd, soundSpeed);
 
    // Get Mach
    Array<OneD, NekDouble> Mach(nTracePts, 0.0);
    Vmath::Vdiv(nTracePts, Vn, 1, soundSpeed, 1, Mach, 1);
    Vmath::Vabs(nTracePts, Mach, 1, Mach, 1);
 
    // Auxiliary variables
    int e, id1, id2, npts, pnt;
    NekDouble rhoeb;
 
    // Loop on the m_bcRegions
    for (e = 0;
         e < m_fields[0]->GetBndCondExpansions()[m_bcRegion]->GetExpSize(); ++e)
    {
        npts = m_fields[0]
                   ->GetBndCondExpansions()[m_bcRegion]
                   ->GetExp(e)
                   ->GetTotPoints();
        id1 =
            m_fields[0]->GetBndCondExpansions()[m_bcRegion]->GetPhys_Offset(e);
        id2 =
            m_fields[0]->GetTrace()->GetPhys_Offset(traceBndMap[m_offset + e]);
 
        // Get internal energy
        Array<OneD, NekDouble> pressure(npts, m_pressureStorage + id1);
        Array<OneD, NekDouble> rho(npts, Fwd[0] + id2);
        Array<OneD, NekDouble> Ei(npts);
        m_varConv->GetEFromRhoP(rho, pressure, Ei);
 
        // Loop on points of m_bcRegion 'e'
        for (i = 0; i < npts; i++)
        {
            pnt = id2 + i;
 
            // Subsonic flows
            if (Mach[pnt] < 0.99)
            {
                // Kinetic energy calculation
                NekDouble Ek = 0.0;
                for (j = 1; j < nVariables - 1; ++j)
                {
                    Ek += 0.5 * (Fwd[j][pnt] * Fwd[j][pnt]) / Fwd[0][pnt];
                }
 
                rhoeb = Fwd[0][pnt] * Ei[i] + Ek;
 
                // Partial extrapolation for subsonic cases
                for (j = 0; j < nVariables - 1; ++j)
                {
                    (m_fields[j]
                         ->GetBndCondExpansions()[m_bcRegion]
                         ->UpdatePhys())[id1 + i] = Fwd[j][pnt];
                }
 
                (m_fields[nVariables - 1]
                     ->GetBndCondExpansions()[m_bcRegion]
                     ->UpdatePhys())[id1 + i] = rhoeb;
            }
            // Supersonic flows
            else
            {
                for (j = 0; j < nVariables; ++j)
                {
                    // Extrapolation for supersonic cases
                    (m_fields[j]
                         ->GetBndCondExpansions()[m_bcRegion]
                         ->UpdatePhys())[id1 + i] = Fwd[j][pnt];
                }
            }
        }
    }
}
 
} // namespace Nektar