Nektar::RiemannInvariantBC Class Reference

Outflow characteristic boundary conditions for compressible flow problems. More...

#include <RiemannInvariantBC.h>

Inheritance diagram for Nektar::RiemannInvariantBC:

Collaboration diagram for Nektar::RiemannInvariantBC:

Static Public Member Functions
static CFSBndCondSharedPtr	create (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)
	Creates an instance of this class. More...

Static Public Attributes
static std::string	className
	Name of the class. More...

Protected Member Functions
virtual void	v_Apply (Array< OneD, Array< OneD, NekDouble > > &Fwd, Array< OneD, Array< OneD, NekDouble > > &physarray, const NekDouble &time)
Protected Member Functions inherited from Nektar::CFSBndCond
	CFSBndCond (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)
	Constructor. More...

Protected Attributes
Array< OneD, NekDouble >	m_VnInf
	Reference normal velocity. More...
Protected Attributes inherited from Nektar::CFSBndCond
LibUtilities::SessionReaderSharedPtr	m_session
	Session reader. More...
Array< OneD, MultiRegions::ExpListSharedPtr >	m_fields
	Array of fields. More...
Array< OneD, Array< OneD, NekDouble > >	m_traceNormals
	Trace normals. More...
int	m_spacedim
	Space dimension. More...
VariableConverterSharedPtr	m_varConv
	Auxiliary object to convert variables. More...
NekDouble	m_gamma
	Parameters of the flow. More...
NekDouble	m_rhoInf
NekDouble	m_pInf
Array< OneD, NekDouble >	m_velInf
int	m_bcRegion
	Id of the boundary region. More...
int	m_offset
	Offset. More...

Private Member Functions
	RiemannInvariantBC (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)
virtual	~RiemannInvariantBC (void)

Friends
class	MemoryManager< RiemannInvariantBC >

Additional Inherited Members
Public Member Functions inherited from Nektar::CFSBndCond
virtual	~CFSBndCond ()
void	Apply (Array< OneD, Array< OneD, NekDouble > > &Fwd, Array< OneD, Array< OneD, NekDouble > > &physarray, const NekDouble &time=0)
	Apply the boundary condition. More...

Detailed Description

Outflow characteristic boundary conditions for compressible flow problems.

Definition at line 49 of file RiemannInvariantBC.h.

Constructor & Destructor Documentation

Nektar::RiemannInvariantBC::RiemannInvariantBC ( 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  )

private

Definition at line 48 of file RiemannInvariantBC.cpp.

References Nektar::CFSBndCond::m_fields, Nektar::CFSBndCond::m_spacedim, Nektar::CFSBndCond::m_traceNormals, Nektar::CFSBndCond::m_velInf, m_VnInf, and Vmath::Svtvp().

    : CFSBndCond(pSession, pFields, pTraceNormals, pSpaceDim, bcRegion, cnt)
{
    // Calculate VnInf
    int nTracePts = m_fields[0]->GetTrace()->GetNpoints();
    m_VnInf = Array<OneD, NekDouble> (nTracePts, 0.0);

    // Computing the normal velocity for characteristics coming
    // from outside the computational domain
    for( int i =0; i < m_spacedim; i++)
    {
        Vmath::Svtvp(nTracePts, m_velInf[i], 
                     m_traceNormals[i], 1,
                     m_VnInf, 1,
                     m_VnInf, 1);
    }
}

virtual Nektar::RiemannInvariantBC::~RiemannInvariantBC ( void  )

inlineprivatevirtual

Definition at line 89 of file RiemannInvariantBC.h.

{};

Member Function Documentation

static CFSBndCondSharedPtr Nektar::RiemannInvariantBC::create ( 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  )

inlinestatic

Creates an instance of this class.

Definition at line 56 of file RiemannInvariantBC.h.

References Nektar::MemoryManager< DataType >::AllocateSharedPtr(), and CellMLToNektar.cellml_metadata::p.

        {
            CFSBndCondSharedPtr p = MemoryManager<RiemannInvariantBC>::
                                    AllocateSharedPtr(pSession, pFields,
                                    pTraceNormals, pSpaceDim, bcRegion, cnt);
            return p;
        }

void Nektar::RiemannInvariantBC::v_Apply ( Array< OneD, Array< OneD, NekDouble > > &  Fwd, Array< OneD, Array< OneD, NekDouble > > &  physarray, const NekDouble &  time  )

protectedvirtual

Implements Nektar::CFSBndCond.

Definition at line 72 of file RiemannInvariantBC.cpp.

References Nektar::CFSBndCond::m_bcRegion, Nektar::CFSBndCond::m_fields, Nektar::CFSBndCond::m_gamma, Nektar::CFSBndCond::m_offset, Nektar::CFSBndCond::m_pInf, Nektar::CFSBndCond::m_rhoInf, Nektar::CFSBndCond::m_spacedim, Nektar::CFSBndCond::m_traceNormals, Nektar::CFSBndCond::m_varConv, Nektar::CFSBndCond::m_velInf, m_VnInf, Vmath::Vabs(), Vmath::Vdiv(), and Vmath::Vvtvp().

{
    int i, j;
    int nTracePts = m_fields[0]->GetTrace()->GetNpoints();
    int nDimensions = m_spacedim;

    const Array<OneD, const int> &traceBndMap
        = m_fields[0]->GetTraceBndMap();

    NekDouble gammaInv         = 1.0 / m_gamma;
    NekDouble gammaMinusOne    = m_gamma - 1.0;
    NekDouble gammaMinusOneInv = 1.0 / gammaMinusOne;

    // 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 > pressure  (nTracePts);
    Array<OneD, NekDouble > soundSpeed(nTracePts);

    m_varConv->GetPressure(Fwd, pressure);
    m_varConv->GetSoundSpeed(Fwd, pressure, 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 eMax;
    int e, id1, id2, nBCEdgePts, pnt;
    NekDouble cPlus, rPlus, cMinus, rMinus, VDBC, VNBC;
    Array<OneD, NekDouble> velBC(nDimensions, 0.0);
    Array<OneD, NekDouble> rhoVelBC(nDimensions, 0.0);
    NekDouble rhoBC, EBC, cBC, sBC, pBC;

    eMax = m_fields[0]->GetBndCondExpansions()[m_bcRegion]->GetExpSize();

    // Loop on m_bcRegions
    for (e = 0; e < eMax; ++e)
    {
        nBCEdgePts = 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]);

        // Loop on the points of the m_bcRegion
        for (i = 0; i < nBCEdgePts; i++)
        {
            pnt = id2+i;

            // Impose inflow Riemann invariant
            if (Vn[pnt] <= 0.0)
            {
                // Subsonic flows
                if (Mach[pnt] < 1.00)
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rPlus = Vn[pnt] + 2.0 * cPlus * gammaMinusOneInv;

                    // - Characteristic from boundary
                    cMinus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rMinus = m_VnInf[pnt] - 2.0 * cMinus * gammaMinusOneInv;
                }
                else
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rPlus = m_VnInf[pnt] + 2.0 * cPlus * gammaMinusOneInv;

                    // + Characteristic from inside
                    cMinus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rMinus = m_VnInf[pnt] - 2.0 * cPlus * gammaMinusOneInv;
                }

                // Riemann boundary variables
                VNBC = 0.5 * (rPlus + rMinus);
                cBC = 0.25 * gammaMinusOne * (rPlus - rMinus);
                VDBC = VNBC - m_VnInf[pnt];

                // Thermodynamic boundary variables
                sBC = m_pInf / (pow(m_rhoInf, m_gamma));
                rhoBC = pow((cBC * cBC) / (m_gamma * sBC), gammaMinusOneInv);
                pBC = rhoBC * cBC * cBC * gammaInv;

                // Kinetic energy initialiasation
                NekDouble EkBC = 0.0;

                // Boundary velocities
                for ( j = 0; j < nDimensions; ++j)
                {
                    velBC[j] = m_velInf[j] + VDBC * m_traceNormals[j][pnt];
                    rhoVelBC[j] = rhoBC * velBC[j];
                    EkBC += 0.5 * rhoBC * velBC[j]*velBC[j];
                }

                // Boundary energy
                EBC = pBC * gammaMinusOneInv + EkBC;

                // Imposing Riemann Invariant boundary conditions
                (m_fields[0]->GetBndCondExpansions()[m_bcRegion]->
                 UpdatePhys())[id1+i] = rhoBC;
                for (j = 0; j < nDimensions; ++j)
                {
                    (m_fields[j+1]->GetBndCondExpansions()[m_bcRegion]->
                     UpdatePhys())[id1+i] = rhoVelBC[j];
                }
                (m_fields[nDimensions+1]->GetBndCondExpansions()[m_bcRegion]->
                 UpdatePhys())[id1+i] = EBC;

            }
            else // Impose outflow Riemann invariant
            {
                // Subsonic flows
                if (Mach[pnt] < 1.00)
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rPlus = Vn[pnt] + 2.0 * cPlus * gammaMinusOneInv;

                    // - Characteristic from boundary
                    cMinus = sqrt(m_gamma * m_pInf / m_rhoInf);
                    rMinus = m_VnInf[pnt] - 2.0 * cMinus * gammaMinusOneInv;
                }
                else
                {
                    // + Characteristic from inside
                    cPlus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rPlus = Vn[pnt] + 2.0 * cPlus * gammaMinusOneInv;

                    // + Characteristic from inside
                    cMinus = sqrt(m_gamma * pressure[pnt] / Fwd[0][pnt]);
                    rMinus = Vn[pnt] - 2.0 * cPlus * gammaMinusOneInv;
                }

                // Riemann boundary variables
                VNBC = 0.5 * (rPlus + rMinus);
                cBC = 0.25 * gammaMinusOne * (rPlus - rMinus);
                VDBC = VNBC - Vn[pnt];

                // Thermodynamic boundary variables
                sBC = pressure[pnt] / (pow(Fwd[0][pnt], m_gamma));
                rhoBC = pow((cBC * cBC) / (m_gamma * sBC), gammaMinusOneInv);
                pBC = rhoBC * cBC * cBC * gammaInv;

                // Kinetic energy initialiasation
                NekDouble EkBC = 0.0;

                // Boundary velocities
                for ( j = 0; j < nDimensions; ++j)
                {
                    velBC[j] = Fwd[j+1][pnt] / Fwd[0][pnt] +
                                VDBC * m_traceNormals[j][pnt];
                    rhoVelBC[j] = rhoBC * velBC[j];
                    EkBC += 0.5 * rhoBC * velBC[j]*velBC[j];
                }

                // Boundary energy
                EBC = pBC * gammaMinusOneInv + EkBC;

                // Imposing Riemann Invariant boundary conditions
                (m_fields[0]->GetBndCondExpansions()[m_bcRegion]->
                 UpdatePhys())[id1+i] = rhoBC;
                for (j = 0; j < nDimensions; ++j)
                {
                    (m_fields[j+1]->GetBndCondExpansions()[m_bcRegion]->
                     UpdatePhys())[id1+i] = rhoVelBC[j];
                }
                (m_fields[nDimensions+1]->GetBndCondExpansions()[m_bcRegion]->
                 UpdatePhys())[id1+i] = EBC;
            }
        }
    }
}

Friends And Related Function Documentation

friend class MemoryManager< RiemannInvariantBC >

friend

Definition at line 53 of file RiemannInvariantBC.h.

Member Data Documentation

std::string Nektar::RiemannInvariantBC::className

static

Initial value:

= GetCFSBndCondFactory().
    RegisterCreatorFunction("RiemannInvariant",
                            RiemannInvariantBC::create,
                            "Riemann invariant boundary condition.")

Name of the class.

Definition at line 69 of file RiemannInvariantBC.h.

Array<OneD, NekDouble> Nektar::RiemannInvariantBC::m_VnInf

protected

Reference normal velocity.

Definition at line 79 of file RiemannInvariantBC.h.

Referenced by RiemannInvariantBC(), and v_Apply().